Although most innovative professional development encourages reflective dialogue among teachers, we still know very little about how such dialogue enables teacher learning. This study describes how teachers make sense of the conflicts among their intended goals and actual practices by responding to their peers' teaching. Four teachers in a large urban high school each taught, evaluated, and shared four lessons they designed to enact self-identified goals absent from their practices. Patterns across the critiques, questions, compliments, and self-critiques that the teachers used to respond to others' lessons indicate the different ways they used the peer context to diversify, personalize, or slow down their thinking about their own teaching, and cross-case patterns reveal how they all learned in ways that would have been less likely in non-peer contexts. The findings suggest why diverse reflective peer groups are crucial starting points for larger professional networks designed to support systemic changes in teacher practices. (Contains 3 tables.)