This study examined the effects of in-service training with performance feedback on preschool teachers' use of classroom preventive practices. Three practices designed to prevent challenging behavior were selected: transition preparations, rule reminders, and social-emotional teaching strategies. Following a brief training on each practice, teaching teams received email feedback on their use of the practice and the effects on child behavior. A multiple baseline design across practices replicated across two teaching teams was used. There were increases in all three preventive practices following training and feedback for both teaching teams. The effects on child behavior were mixed. (Contains 2 tables and 2 figures.)