This study examined processes that may impact implementation fidelity in the course of an effectiveness evaluation of the WITS Programs in which all school were implementing the programs. The programs were being implemented in 16 elementary schools in rural or suburban school districts from Alberta, Ontario, and New Brunswick. We assessed indices of implementation fidelity as well as teacher integration of program strategies into their daily practice, and children’s use of WITS strategies (CUoPS) four times over two academic years. We examine the stability of and interactions among fidelity, integration, and CUoPS and also examine their impact on intervention outcomes targeted by the WITS Programs.