Objective: This systematic review evaluates the content of effective support provided to practitioners of evidence-based interventions in order to establish and maintain treatment integrity. Method: Four articles covering six outcome studies are included in this review, these studies (1) adequately operationalized treatment integrity procedures and (2) showed sufficient effects of the support on levels of treatment integrity. Results: The results show that an effective support system consists of a minimum combination of training and ongoing support (supervision, consultation, and coaching), preferably extended with booster sessions. Conclusions: The review provides specific information on effective content of this support which practitioners and intervention developers can use in order to establish and maintain treatment integrity of their planned interventions.