This study used developmental theory to examine changes in four preservice physical education teachers’ pedagogical content knowledge during a 20- lesson middle school volleyball unit. Participant observation methodology was used including interviews, field observations, and document analysis. Data were analyzed using constant comparison. Three main shifts in their knowledge were identified. First, the teachers moved from poorly predicting students’ skillfulness and blaming students when those predictions caused problems, to valuing the matching of tasks to students’ skill levels. Second, they understood motor development differently as their inability to recognize skill development caused problems in helping students learn, and they were then mentored by experienced teachers to better see and facilitate learning. Third, the preservice teachers grew to respect and emphasize student emotion in teaching, realizing that overlooking emotion led to problems in teaching. The discussion focuses on common pitfalls in teacher development and the need for attention to emotion in the research on teacher knowledge.