This article shares our experiences and surprises as we developed, implemented and evaluated a 12-week faculty development program for registrars as clinical supervisors over three cohorts. The program has consistently been rated highly by participants. Yet, following a comprehensive curriculum review, we were surprised that our goal of encouraging identity development in clinical supervisors seemed to be unmet. Whilst our evaluation suggests that the program made important contributions to the registrars' knowledge, application and readiness as clinical supervisors, challenges linked to developing a supervisor identity and managing the dual identity of supervisor and clinician remain. In this article we describe our program and argue for the importance of designing faculty development programs to support professional identity formation. We present the findings from our program evaluation and discuss the surprising outcomes and ongoing challenges of developing a cohesive clinical educator identity. Informed by recent evidence and workplace learning theory we critically appraise our program, explain the mechanisms for the unintended outcomes and offer suggestions for improving curricular and pedagogic practices of embedded faculty development programs. A key recommendation is to not only consider identity formation of clinical supervisors from an individualist perspective but also from a social perspective.