This longitudinal qualitative multicase study of social studies teachers' implementation of differentiation examined two educators' experiences as teacher candidates and beginning teachers, drawing upon theoretical perspectives of novice teacher appropriation of pedagogies across learning-to-teach settings. The study's first phase explored how participants conceptualized differentiation and anticipated implementing it in future practice as they learned about it in depth and with fidelity in a teacher preparation course about this pedagogical approach. The second phase examined how, as first and second-year teachers, participants' conceptions of differentiation evolved as they gained experience, participants implemented differentiation, and contextual factors shaped their conceptions and implementation. Extensive data collection across three years supported rich exploration of the evolution of participant experiences. Findings indicated that when their early career social studies instruction involved fact-focused curricula rather than authentic disciplinary inquiry, participants did not see meaningful differences among students or a corresponding need for differentiation.