Recently, rationale development has received renewed attention as a core theme of social studies teacher education. To date, however, this interest has yet to spark a significant body of research. This study addresses the gap between recommendations and research regarding rationale development in teacher education programs and the rationale-based practices of first-year teachers. In this article, the author discusses findings from a year-long, qualitative, multiple-case, case study that examined the problems and possibilities of rationale-based practice in social studies classrooms. Three themes emerged during data analysis: (a) teacher versus "the system," (b) rationale meets reality, and (c) built-in guilt. These themes demonstrate that rationale-based practice is possible; however, gaps exist between ideas in participants' rationales and their practice as first-year teachers. As such, teacher educators need to reframe programs and courses around rationale development and implementation to help bridge this gap. (Contains 3 tables and 2 notes.)