This paper reports the results of a qualitative study that examined the experiences of six preservice English language teachers in Hong Kong as they prepared for, engaged in, and reflected upon a compulsory research project during the final year of their Bachelor of Education degree program. Drawing upon in-depth interviews and using methods of discourse analysis, the study considers how the student teachers' expectations and experiences of a compulsory research project shaped and were shaped by the construction of their professional identities. The results illustrate the identity conflicts the preservice teachers experienced as their research engagement required that they cross institutional and educational boundaries to confront, question, and reject various identity positions, including "student teacher," "full-time teacher," and "teacher-researcher." Implications for how schools and teacher education programs that include a compulsory research component might support preservice teachers during such identity formation experiences as well as for future research are discussed.