Principles of effective evidence-based intervention are presented. Topics discussed include: evidence-based practice (EBP); term clarification; eight principles for effective interventions -- assess actuarial risk/needs, enhance intrinsic motivation, target interventions, skill train with directed practice, increase positive reinforcement, engage ongoing support in natural communities, measure relevant processes/practices, and provide measurement feedback; components of correctional interventions; implementing EBP principles; applying the principles at the case, agency, and system levels; seven recommended strategies for implementing effective interventions; and levels of research evidence.