This study examines how graduate teaching assistants of composition and peer and professional tutors of writing develop their identities as teacher and tutors in preparation programs. Research in teacher education programs indicates that when preparatory sessions highlight the concept of teacher identity in the preparation of K-12 teacher candidates, teacher candidates have higher levels of teacher efficacy, job satisfaction, and retention in the field (Danielewicz, 2001; Alsup, 2006; McKinney et al., 2008). Because writing TAs and tutors account for much of the composition instruction and support of undergraduate writers, the preparation programs of these two groups would greatly benefit from the same attention to teacher identity as in the preparation of K-12 teachers. This study considers three central issues: first, it investigates the types of identities that are encouraged and/or fostered in the preparation of TAs and undergraduate tutors of writing at two sites, referred to as The University and The Community College. Second, it examines whether or not the identities promoted in the preparation modes at The University and The Community College reflect the philosophies of the preparation programs. Third, it considers how the construction of identity affects the tutoring or teaching practices of the participants. These questions provide a framework through which the development and presence of teaching or tutoring identities in the study's participants are examined. Three case studies of preparation programs were observed preparing either TAs or tutors. Data were drawn from fourteen self-selected participants across three cases: four undergraduate students from a four-year university; four professional writing tutors from a community college; and six graduate TAs all teaching composition. All preparatory sessions were observed across the three cases. Each subject's teaching or tutoring practices were observed two times, and within a week of each observation, the subjects were interviewed regarding the observation. These data were analyzed as individual cases and in parallel. The resulting themes are presented as a heuristic of teacher identity characteristics along a novice-to-expert spectrum focusing on four characteristics: content knowledge and behaviors; flexibility in theory and practice, membership in a peer community, and engagement in reflective practices. The majority of the participants developed teacher or tutor identities consistent with the goals of the program in which they were prepared and displayed evidence of the teacher identity characteristics in their practices. Among those not included in the majority, one subset developed identities that were not aligned with the preparation program; another developed identities reflecting the goals of the preparation program but were not aligned with best practices in the field. [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.]