Despite the growing evidence base for the efficacy of preventive interventions, the level of implementation of these interventions in schools is often less than optimal. One promising approach to supporting teachers in implementation of interventions is the use of coaching. In this study, teachers were trained in a universal classroom management intervention and provided ongoing coaching. The association between the type and amount of coaching activities and teacher implementation of proactive classroom management over time were investigated. Results indicated that teachers who received more performance feedback had higher levels of implementation over time in comparison with teachers who received less feedback. In addition, a significant interaction between the amount of coaching a teacher received and his or her implementation of proactive classroom management was found. Increased implementation over time was observed for teachers with lower initial levels of implementation who received more coaching, whereas implementation decreased over time for teachers who received less coaching. The importance of coaching as a support system for enhancing implementation quality of classroom-based preventive interventions is discussed.