This dissertation is based on a case study of 8 beginning English teachers who participated in a collaborative inquiry group at an urban, comprehensive, high school in the San Francisco Bay Area. Qualitative data (including audio-transcribed meeting data, individual interview data, and classroom observations) were collected over two school years, with a follow-up interview about teacher professional identity conducted in the school year following the dissolution of the inquiry group. The study utilizes a theoretical framework grounded in notions of agency, power and discourse as critical elements in the social construction of identity to examine how the focal teachers construct and enact a teacher professional identity in their early careers. Teacher professional identity is defined as the beliefs, values, and commitments an individual holds toward being a teacher (as distinct from another professional) and being a particular type of teacher (e.g. an urban teacher, a beginning teacher, a good teacher, an English teacher, etc.) The data indicated three types of factors that were important to focal teachers in establishing their early professional identities. The first type was individual factors such as personal experiences as students and pre-professional teaching experiences. A second group included practice-based or classroom-related factors such as subject matter, curriculum, instructional planning, and classroom based goals. Finally, the third type was connected with external discourses related to teaching and learning. These discourses came from theory, policy, contexts in which teachers were embedded and from collegial or expert models of practice. While all three types of factors were important to the focal group of teachers, individual teachers were oriented toward a particular set of factors over others in the construction of their professional identities. The orientation of teachers had consequences for their classroom practice as well as their sense of what it meant to be a teacher professional. The teacher who emphasized individual factors, constructing his teacher professional identity around a personal image of teaching, was described as an individually-oriented teacher. Teachers who emphasized classroom practice as the focal aspect of their identities were considered classroom-oriented teachers. Teachers who approached their classroom practice and professional decision making with a clear sense of external discourses related to teaching and learning and a sense that they might affect these discourses through their professional practice were called dialogically-oriented teachers. Dialogically-oriented teachers were the only group of teachers able to articulate both their classroom practice and the thinking which was underlying their choices as teachers. The collaborative inquiry group was embedded in a parent program which advocated a dialogically-oriented approach to teacher professionalism. Group meetings were structured to promote such a stance toward professional identity. The data indicated that there was a predominance of dialogically-based interactions within inquiry group meetings; however, in examining these interactions more closely, teachers' individual professional identity orientation connected closely with the focus and nature of their participation in the inquiry group. Further, although classroom-oriented and individually-oriented teachers engaged in various forms of dialogic interaction within meetings, these types of interaction did not seem characteristic of their self-descriptions of their own teacher professional identities. Implications of the study include: the importance of advocating a stance toward teaching as a profession; investing in teacher education programs which promote a dialogically-oriented stance toward teaching; exploring the expansion of university-based partnerships between the pre-service and induction phases of teacher education; promoting increased dialogue between K-12 teachers and educational researchers and encouraging a broader audience for educational research, particularly research focused on teaching and learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]