Over 25,000 U.S. schools have adopted and are in various stages of implementing Positive Behavioral Interventions and Supports (PBIS), an education-specific application of Positive Behavior Support (PBS). Among the plethora of evidence-based curricula, interventions, and innovations, PBIS is among the few evidence-based frameworks in education that are being implemented at this scale. For this reason, it is important to celebrate the past efforts that have brought the field to this level of adoption and acknowledge that, as a research tradition, we are at a pivotal point. One in four schools in the United States are implementing PBIS, which can be argued that we have arrived at critical mass as it relates to the theory of diffusion (Rogers et al., 2014). This context is key because the proportion of schools within a school district already implementing PBIS is a powerful predictor of sustained implementation (McIntosh et al., 2018). Some might state that PBIS researchers and implementers should stay the course, what has worked will keep working, and the rate of PBIS adoption and positive outcomes will continue as it has over the last 20 plus years. But what can research tell us? In this chapter, we will introduce an aligned, multidisciplinary field of work called implementation science that aims to support both practice and research with the goal of eliminating the “research to practice gap” while also positively supporting the continued diffusion of evidence-based practices such as positive behavior support.