Educators around the world have consensus on the significance of teacher learning in meeting the complex challenges of 21^st century in the field of education. This consensus has led to the realization that achieving organizational objectives would require teachers, teacher leaders and top management to play an active role. Change in school demographics and introduction of technology for swift development is essential to individuals having the potential to encourage creativity and effectively handle learning complexity (Crow, 2001). The emphasis on continuous professional learning and growth for teachers can be seen in the field of general education as well in TESOL in the context of incessant developments that require teachers to possess top-notch knowledge of the field in order to impact pedagogical practices in educational organizations and ensure their contribution to students' learning outcomes.

Teachers' endeavors to expand their pedagogical skills' repertoire and improve instructional practices in their ever-changing contexts give them a chance to nurture a robust classroom identity and emerge as a credible and competent professional. Moreover, their intrinsic motivation produces urge for more learning and competence as a teacher. It creates opportunities for them to assume a leading role in their institutions, establish their identity as teacher leaders and perform roles beyond classroom boundaries by teaching learners and guiding, influencing and motivating colleagues toward improved instructional practices. These leadership responsibilities have implications for individuals in their roles as well as for institutions at large as teacher leaders play an essential part in both the operation and organization of educational institutions.

While performing leadership roles in the context of an educational organization, teachers negotiate their position and identity through a continuous process of interaction with others (Varghese et al., 2005) that creates an environment of collegiality and leads to the acceptance of each other. Subsequently, the formation of a new identity takes place as teachers switch their instructional roles to leadership positions in a school context. Such individuals are called teacher leaders or instructional leaders whose diverse strategies with colleagues and coworkers focus on change. They are also supported by others in the collaborative role which add to the collective professional knowledge (Frost, 2010). These responsibilities enable a teacher to construct identity as a leader and perceive him/herself as a teacher leader in a context-specific leadership role. However, identity formation cannot be restricted to a specific context or roles and it continues to emerge in new forms, "as people widen their social networks and the contexts in which they live and work, they continue to re/construct and to transform their position over time in a specific relation either to new individuals or groups they interact with and the new roles they take on in new contexts of action or communities of practice" (Pennington & Richards, 2016, p. 7).

Review of previous studies suggests that development of teacher identity and leader identity are widely researched areas in mainstream education. However, there is dearth of evidence in the relevant literature with regard to teacher leader's identity construction in the field of Teaching English to the Speakers of Other Languages (TESOL). This theoretical study highlights the scope of teacher leader's professional identity construction in education and the same is explored via the lens of professional identity formation and supported via relevant literature that might be helpful to TESOL researchers to consider it a potential area of investigation in the future. As the aim of this theoretical review is to conceptualize teacher leader's professional identity in TESOL through the lens of professional identity formation, this study theoretically explore, a) what is identity, how is professional identity of teachers perceived in the field of education, and what factors might contribute to the construction of teacher leader's identity in the field of TESOL?

The notion of identity is primarily derived from the Greek concept of persona or mask, which lets people to be either in a particular position or play definite roles in any given community (Hollis, 1985). Identity is widely explored in fields such as social psychology (Tajfel & Turner, 1986), sociology (Bernstein & Olsen, 2009), economics (Akerlof & Kranton, 2000), and developmental psychology (Bosma & Kunnen, 2008). As the concept has been discussed in various fields so there is no definition of identity which can be used as a framework, model or point of reference in empirical research. However, scholars have suggested a wide range of definitions, which can fit the purpose of a study in a given context.

In the most recent work of Pennington (2015), "identityis considered as the unique set of characteristics and features associated with a particular individual relative to the perceptions and characteristics of others" (cited in Pennington & Richards, 2016). These characteristics of a person may include his/her social, cultural, religious, educational, professional and socio-economic background, affiliation and status. Additionally, it may be their skills, abilities and personality attributes which other people associate with them. However, an individual may adopt a different identity in a different context depending on his/her role, for instance, a classroom teacher can have a teacher identity in school as a teacher or a colleague while at home s/he has an identity as a parent or spouse (Pennington & Richards, 2016). Burke (2003) categorizes identity into three distinct categories that is, a) social identity, b) personal identity, and c) role identity. Social identity denotes people's belonging to a specific group (Tajfel, 1982), such as African-American, British-Pakistani, Democrats, etc. Personal identity means how someone is perceived based on their personal characteristics, for instance fairness, nobility, partiality or impartiality, which may or may not be the identities of others. Role identity refers to the various patterns of behavior related to contexts and social interactions of individuals as mothers, teachers, presidents, or husbands etc. (Burke, 2003). In relation to contextual and social interactions of individuals, role identity is close to the individuals who operate in educational institutions.

As personal identity refers to an individual's attributes, traits and abilities, it contrasts with social identity, which is comprises various group classifications (Ashforth & Mael, 1989). Tajfel (1981) defines social identity as "part of an individual's self-concept which derives knowledge of his membership from a social group". Social identity theory is mainly concerned with examining the part thatcollective selfplays in a group and intergroup processes through which a link can be established amid collective phenomena, and social cognition and behavior of an individual (Hogg & Ridgeway, 2003). In this respect, Muir (2014) perceives identity theory as "small groups' and units' sociological study within a larger society, which bonds their identities to the role associations and role-related behaviors that they engage in". Self is therefore, a social construct that develops an individual to perform a specific role (Stryker & Burke, 2000).

Other scholars define identity in various ways that include an individual's disposition in a particular context of a given culture or community (Aydeniz & Hodge, 2011). Burke (2004) defines identity as "the sets of meaning people hold for themselves that define 'what it means' to be who they are as persons, as role occupants, and as group members" (p. 5). According to Caldron and Smith (1999), identity is a sense of the self, a status associated with a social context created through interlinking both personal and social biographies. For Volkmann and Zgagacz, (2004), "dentity is 'an ongoing internal construction that prepares one for taking action' (p. 600). Other theorists provide a different perspective and consider it identity narrative showing the multifaceted nature of one's identity as 'a product' that how one sees himself and as 'a process' that is continuous interaction with others (Beauchamp & Thomas, 2009). In a similar way Sfard and Prusak (2005) define identities in relation to the way collective discourses work form personal worlds and contribute community's voice.

Furthermore, identity not only develop via an individual's self-reflection but also through the way other people see that particular person as an individual (Sfard & Prusak, 2005). Similarly Day, Harrison and Halpin (2009) considers identity facilitating an individual in knowing and assessing themselves, identifying their goals and aspirations, unveiling their personal strengths, and challenges they are either facing or might face. They also believe that the culmination of one's attributes, values, knowledge, experiences and self-perceptions define identity. While highlighting ESL/EFL setting, Richards (2009) explains identity individuals' self-perception and how they proclaim different roles in different settings. Giddens (1984) considers identity as an integral part that individuals use in the process of interaction for constructing social structures and systems. Furthermore, individual pursuit of identity is one of the fundamental aspects in exercising agency He also believes that the pursuit and enactment of self-identity by individuals is a key aspect of their development of agency, a process indispensable for individual will and practice (Gee, 2001, Greenfield, 1993).

The idea of developing an identity is considered multi-dimensional and multi-layered (Danielewicz, 2001), which involves social and individual elements and context-specific professional tasks (Aubrey, David, Godfrey & Thompson, 2000; Beijaard, Meijer & Verloop, 2004). It is a common notion that work-related self-identities are developed through interactions of individuals in a variety of ways, grounded in their biographies, dispositions and job experiences (Nias, 1999). This shows the personal and social dimensions of identity that has been widely discussed in the literature (Clark, 2013). Individuals also go through a series of constant differentiation and integration events, steered by subject-object relations. They become conscious of their context, role and responsibilities and make sense of their experiences (a process that leads to the identity formation).

Day, et al. (2009) note that an individual may not work on his or her identity development in cases he or he is not open to information either through self-reflection or feedback. This signifies one's positive attitude to professional learning and growth. Similarly, unsupportive environments may prove detrimental for individual development; however, conducive environments offer role models, expectations, and support in an organizational context. As a final point, the outcomes of previous professional development courses, training and mentoring can prove effective in shaping a new identity whereas negative developmental or learning experiences of the past might significantly impact an individual's identity.

In the late 20^th century, the concept of professional identity development was viewed as a process that helped individuals internalize occupational identifications (Becker & Carper, 1956). Since the beginning of 21^st century, scholars have perceived professional identity a broader term associated with an individual's understanding of the self, personal experiences, and sense of belonging within diverse professional and social groups (Seemiller & Priest, 2015). Similarly, professional identity is the production of self-perception and legitimization by others and an individual's role within society or workplace based on his/her interactions and relationships with peers or colleagues that give him/her an identity and status (Sutherland, Howard & Markauskaite, 2010).

Professional identity facilitates individuals to realize the essence of their profession facilitating them to perform their role, viewpoint about others within the same social group and the social world outside and outside (Brott & Myers, 1999). An individual's professional identity depends upon his or her personal perceptions of self-image and self-efficacy in relation to their working context (Busher, 2005). Scholars consider identity integral to an individual's sense and exercise of agency created through exchange of ideas with others in their workplace setting (e.g. Giddens, 1991; Busher, 2005). Further, professional identity development is an ongoing process that enables an individual to comprehend the present situation in contrast to future expectations (Rhodes, 2007; Beijaard et al., 2004). Likewise, Busher (2005) states that identity is primarily associated with an individual's personal history and lived experiences (Busher, 2005).

Professional identity of individuals is important to their professional role, their relationship with colleagues and their affiliation with the workplace. Hanuscin, Cheng, Rebello, Sinha and Muslu (2014) highlight the significant impact on identity on professional role wherein they consider it as an important theoretical framework for studies in educational contexts. According to their understanding, identity construction nourishes teachers become teacher leaders. In educational leadership, it is important to gain a sense of identity formation of the teacher leaders in order to understand how individuals raise an awareness of themselves as who they are and how their identity construction contributes to leadership development. Hanuscin et al. (2014) further state that the increasingimportance of studying teacher leadership, very few teachers think of their status as leaders for to be a teacher leader does not necessarily mean acquiring knowledge and particular skills; rather, it signifies a process of evolving a new professional self. Nonetheless, research on teacher development to teacher leader with reference to identity negotiation in TESOL setting needs further exploration.

The notion of professional identity construction is extensively discussed. Sachs (2005) considers professional identity "how to be", "how to act", and "how to understand" their roles in society (p. 15). The process of becoming, acting and understanding is an iterative one as teachers continue to develop themselves as teachers and define themselves. It shows that the professional self of teachers develops over career stages based on their social and professional status and they choices they make in their social and professional settings (Coldron & Smith, 1999). Coldron and Smith (1999) argue that professional choice of work related to things such as the way teachers plan lessons and use their repertoire of activities rapports not only in the classroom but also in the school community. Thus, the professional identity of teachers is developed from their own perception of themselves, their status in society and the choices they make in their organisations.

Literature highlights two significant elements thought to be of core importance in professional identity construction: first, acknowledging sub-identities (e.g. Beijaard et al., 2004); and second the concept of exercising agency as teachers while actively participating in the process of confirming their professional development, which consequently facilitates identity construction (e.g. Coldron & Smith, 1999). Rhodes (2007, p. 160) states that elements of teachers' professional identity construction could be useful to teachers becoming leaders, challenges they face in their day-to-day leadership practices and experiences with colleagues, managers, and other school leaders. Consequently, teachers establish their own leadership identities and improve on any weaknesses in their professional practices.

Luhrmann and Eberl (2007) perceive leadership identity as a strategic self that is constructed through experience as indicated by identity theory. In a similar vein, van Knippenberg, De Cremer & Hogg (2005) ascertain the understanding of identity approach to leadership dependent on the ways that we perceive ourselves as our own identity convincingly reflects our feelings, beliefs, attitudes, goals, and behavior. Identity development and leadership learning are interlinked concepts. Leader's identity is considered an important aspect of leadership development which helps leaders in understanding of who they are and how they think of themselves as leaders (Day, 2001). Leadership begins with self-discovery and understanding of one's role as a professional. This realization enables individuals to see themselves as leaders.

The concept of identity development as a leader is widely discussed in educational and non-educational literature. As leaders play a key role in the successful operation of organizations, individuals in leadership roles require to build on their existing knowledge, acquire new skills and enhance their efficacy in a bid to contribute to the organizational outcomes. The whole process is about discovering and transforming oneself and developing a new identity as a leader.

In an endeavor to connect educational leaders' identity construction and professional development, Muir (2014) states that most of the existing literature on teachers, highlight skills building. Hernez-Broome & Hughes (2004) state that despite widespread research on leadership development processes and methods, research concerning identity development is still limited.

Muir (2014) also found out that identity development can be influential in educational contexts. Basic skills such as behavioral, intellectual, and social are prerequisites of leadership in an organization (Lord & Hall, 2005). According to Lord and Hall for sustainable and successful leadership, it is essential that leadership becomes part of an individual's identity. For Luhrmann and Eberl (2007), four issues related to the dynamics of leader identity formation are: i) motivation, ii) conformity and authenticity, iii) power, and iv) relationships. They propose a leader identity development process comprising four phases that includes, "a) identity negotiation, b) identity balance, c) task interaction, and d) identity conflict and negotiation. In addition, the formation of a leader identity is a key to understanding the process of leader development" (Lord & Hall, 2005). They emphasize on three significant points related to the nature of identity from critical perspective, which are:

Concerning leadership identity, Komives, Owen, Longerbeam, Mainella, and Osteen (2005) identified potential phases in the course of identity construction of leaders. Their research specifically focused on leader identity development and defined leadership identity as a process incorporating one's personal and social self-enabling an individual get a distinctive position difference and work with others effectively for accomplishing the given tasks associated with recognition. This model illustrates that passing through these stages, individuals achieve profound comprehension of leadership roles in themselves and in relation to others in their organizational settings.

Moreover, student leaders on this study acknowledged having multiple social identities which played a crucial role in developing a leadership identity. This idea can be found in other researchers' work as well. For example, to Petriglieri (2011), leadership learning is associated with an identity of workspace which considers three areas: the experiences of participants as leaders and followers, understanding their lived experiences as part of their identity formation, and making sense of their feelings and the role of unconscious. Bass (1990) claims that this sense making of social experiences and emotions influences their leadership performances because leadership development is a continuing process taking place among peers, superiors, family, and friends and plays role in shaping one's consequent performance as a leader.

It can be inferred from the above discussion that individuals develop identities based on their sense of affiliation to a group in their workplace. In the process of identity development, individuals reflect to see and relate themselves not just to the present, but to future as what they want to become. The following section presents the definition of professional identity and attempts to understand how individuals develop their professional identities in educational contexts.

Educational literature suggests a link between leadership learning and identity Construction of a leader that helps leaders in understanding who they are and how they think of themselves as leaders (Day, 2001; Petriglieri, 2011). Identity development as a leader is an integral part of development (Lord & Hall, 2005). Moreover, they believe that the concept of leadership identity formation is a context-bound phenomenon based on interactions, experimentation, reflection and learning in the teachers' workplace.

A plethora of studies has investigated the leadership identity formation of teachers in various contexts around the world. This studies give an insight into factors that can help teachers in developing their leadership identity. Margolin's (2007) retrospective study presents an example of work-related identity that she formed over the period of four years. In her reflective account, Margolin examines how she formed "a new professional self that revealed a noteworthy shift in her opinion of leadership from a transactional model via a transformational model and hence, to a distributed leadership".

Likewise, scholars associate professional identity of teachers with their professional development as teacher leaders. White (2013) examined seven experienced teachers' perceptions of assuming the roles of leading subject knowledge development of both new and experienced teachers guided by a case-study design. She discovered that teachers' professional identity had a significant impact on leading professional development. This realization of teacher educator identity could be the outcome of professional development program or other contextual factors, which require more investigation in various educational contexts.

Developing a comprehensive understanding of self-identity could possibly be due rapid shift of context and identity formation is a dynamic, and career-long process for teachers (White, Roberts, Rees & Read, 2013). Katzenmeyer and Moller (2009) emphasize teamwork between teachers and teacher leaders as it helps them grow as individuals, expand their circles of influence through focusing on their own and colleagues' growth at workplace.

Organizational contexts and school cultures are considered important factors in shaping leadership identities. As leadership identity of teacher leaders in a school context not only enables them to perform effectively as leaders, it gives them an opportunity to see themselves as leaders. This perception of 'self' signifies an individual's identity that teachers construct in their workplace while performing various professional roles and responsibilities. In educational settings, teachers get a chance to learn new things while performing wide-ranging roles i.e. classroom teachers or teacher leaders, which contribute to the shaping of new identities. If the context offers support and learning opportunities then teachers can quickly develop their leadership identities. In their work with teacher leaders, Katzenmeyer and Moller (2009) wondered why teachers were hesitant to be called leaders even when they were active in leadership activities. Irrespective of their origins, they found that teachers were reluctant to be called leaders owing to unsupportive school cultures. Levenson (2014) also notes that in learning organizations, support from top leadership and administrators play a key role in developing teacher's leadershipidentity.

Seemiller & Priest (2015) also cite authors who emphasize the vital part that school context can play in the process of identity construction, especially for novice teachers or teacher leaders such as Archer, Sutherland, Howard, & Markauskaite. A number of factors can influence teachers' identity, for instance, school culture, leadership models or structures in schools, professional learning communities, campus-based professional development courses or program, professional networking and collegial practices in the school (Seemiller & Priest, 2015). These influences may vary from context to context; therefore more research in this direction can facilitate educators to make more informed decisions based on the research findings.

White (2013) reveals that professional growth affects teachers' identity in school context. While exploring identity construction in South African school leadership context, Moorosi (2013)finds identity as a dynamic process through leadership development program. Likewise, in a case study Collay (2014) found an American Latina teacher Cecilia moving as a leader from her classroom domain to her grade level team first, then to school leadership team, and finally to school district personnel. This transformation indicates how the woman of color integrate personal, professional, and cultural experiences to identity development as a leader.

Muir (2014) focuses on the research how student teachers and their learning experiences of the mentoring program help them develop professional identity. His findings advocate that "adult learning principles as instrumental components to teacher leader identity development. In the similar vein". Judkins (2014) found that teacher leaders took leadership identities as something integral to their identity as teachers unlike their classroom identities though.

Apart from the influence of the organizational context, teachers' competence, efficacy and ability also shape their leadership identities. Literature suggests that credibility as a classroom teacher is one way to establish a strong leadership identity. Teachers who lack reputation as a classroom teacher may fail to gain the confidence of his/her colleagues and the top management. Credibility can only be achieved by those who have competence to and lead simultaneously. In addition to credibility as a teacher, awareness of one's strengths and weaknesses assist teacher leaders to take appropriate decisions. Seemlier and Priest (2015) calls it a personal agency, which they believe, becomes a source of professional identity development. Personal agency refers to one's capability of exercising the power of controlling one's own motivation, thought processes, and actions (Bandura, 1989). Teacher leaders with high personal agency are aspirational and motivated individuals who have high goals self-belief to achieve anticipated outcomes (Bandura, 1989). Reliance on personal agency can help teacher leaders to make sense of their challenging experiences, achieve their objectives, establish themselves and develop a leadership identity. Such individuals try new situations and experimentations that enhance their self-efficacy. Self-efficacy often adds to the individual's expertise, subject matter and knowledge, which can also impact a teacher leader professional identity (Kogan, 2000).

According to Kaminski (2011), previous teaching experience can lead to teacher leader efficacy and subsequently help him/her to form a strong leadership identity. In addition, Seemlier and Priest (2015) consider previous knowledge an important factor in identity formation of educator. They believe that "the more one knows about leadership, the greater one's confidence or belief might be in one's own abilities of executing their choices for constructing particular identities".

As establishing a leadership identity is deemed a personal landmark in teachers' professional context, their utmost desire to learning becomes a driving forces for them which result in a new professional identity as leaders. Danielson (2006) states that traditionally teachers with leadership inclinations in various educational contexts, either yearn to achieve greater influence in their workplaces or become administrator in teachers' unions. She also thinks that such teachers continue their teaching but have a desire to exercise leadership roles as administrators. It is this intrinsic motivation that pushes them to nurture a new professional identity.

Literature on the issues of leadership development and leader identity mainly focuses on top leadership roles and their organizational effectiveness in higher education institutes around the world. Consequently, little consideration is shown for mid-level leadership; very little empirical research is available on the development of mid-level leadership (Smith, 2005), and existing studies often indicate what leaders do rather than why and how they do it. Moreover, the processes of identity formation of leaders that is part of leadership learning and development are not clearly defined in the literature. Ribbins and Gunter (2002) also draw attention to a serious dearth of literature on leaders with reference to what leaders are, who shape them into what they are at a given point of time and how they achieve the position of a leader. This assertion shows the importance of recognizing the process of how leaders learn to lead and develop a leadership identity, which can be equally important in the field of TESOL.

For language teachers, it is considered a great achievement to initiate their careers as language teachers and establish themselves as teacher leaders, such as curriculum coordinators, heads of academic units, mentors and teacher trainers. Although it is unclear that how these TESOL teachers move to the leadership positions in TESOL and if any due process of appointment is followed. Notwithstanding the undefined criteria for teacher leaders' selection, their role is considered crucial for their ability to undertake major tasks, influence change and reforms and work as a connection between the leaders on top and teachers. Furthermore, their exemplary leadership skills and strong leadership identity can have an impact on educational affairs in their workplace. However, it is unknown how these teachers develop their leadership identities while performing leadership roles. Further research can contribute to the body of knowledge in the field of TESOL.Since there is little research in this area in the EFL/ESL context, particularly in Pakistani context, researchers can adopt a variety of research methodologies to explore professional identity construction of teacher leaders. For instance, mixed-method design, narrative inquiry, case study and experimental design will help investigators to understand the research phenomenon and answer questions related to:

Professional identity and identity development are discussed in educational and non-educational literature. Although numerous studies have explored teacher identity and identity formation of educators, there is still lack of research focusing on teacher leader identity construction in TESOL. Hence, more research in identity journeys can provide insights into how teacher leaders develop their leadership capacities. In this respect, this paper may guide experienced and prospective teacher leaders in mainstream and TESOL education to continue developing their leadership identities by working collaboratively with their colleagues in their workplace contexts. Understanding the processes of identity development can contribute to recruitment and retention of EFL teacher leaders and enhance their professionalism.