The idea that underlies the response-to-intervention model (RTI) is relatively simple. However, educators find its implementation more complex than anticipated. As for any improvement project in education, the successful implementation of RTI requires a planned and rigorous professional development (PD) program. The international literature on the subject shows that PD is the most effective means of improving the quality of teaching. A systematic review of research allowed us to identify five principles for an effective PD program. These principles are introduced and explained. Then, a successful application of these principles is described in the implementation of an RTI model at the Rivière-du-Nord School Board in St-Jérôme, Québec.