A majority of evidence-based interventions in schools are delivered through consultation models and are implemented by a mediator, such as a teacher. Research indicates that mediators do not always adequately implement adopted evidence-based interventions, limiting their effectiveness in transforming student outcomes. We propose that to transform student outcomes through evidence-based practice, conceptualization of mediators' intervention implementation must move beyond quantification of discrete intervention steps implemented. Intervention implementation requires behavior change and thus can be conceptualized as an adult behavior change process. The purpose of this article is to illustrate how adult behavior change theory may inform how intervention implementation is conceptualized, facilitated, and supported. An empirically supported theory of adult behavior change from health psychology, the Health Action Process Approach, and how it has informed development of PRIME (Planning Realistic Intervention Implementation and Maintenance by Educators), a system of supports to facilitate mediators' implementation of school-based interventions, are introduced. A case study demonstrating the application of PRIME with a public school teacher implementing a behavior support plan is presented. Implications for future research are discussed.