The focus of this special issue is on identifying factors that predict a school's likelihood of high implementation of socialemotional learning (SEL) interventions. In this case, these factors are interpreted as readiness to implement. Implementation readiness is defined by the editors as the capacity to implement an evidence-based intervention (EBI) effectively. Though not stated explicitly, readiness in this definition seems to be a characteristic of the implementers (i.e., teachers or school). The model proposed by the editors and reflected to varying degrees by each of the seven studies involves documenting variables of teachers, classrooms, and schools that are predictive of high-quality implementation and using those variables to create readiness profiles and tailor implementation supports.SEL programs have demonstrated convincing efficacy for improving the social and academic development of children (Durlak et al. 2011). As practitioners and policy makers become more convinced of the fundamental importance of SEL as a foundation for quality education and child development, the challenge of effectively scaling SEL programs and practices is becoming more critical and timely. This special issue addresses an important empirical question: Can we identify factors that represent Breadiness^of a school (and its teachers and classrooms) to adopt an SEL program and deliver it with sufficient quality and fidelity to reproduce the improvements in social and academic outcomes demonstrated in controlled trials? The seven SEL implementation studies presented in this special issue depict a complex picture of delivering SEL programs in schools and assessing both implementation and impact. As a result, across these seven studies, and other similar studies, we arrive at a long laundry list of variables that may influence implementation quality, fidelity, and reach (which may in turn potentially impact program effects and sustainment).So what can be made of the complex readiness model characterized across these seven studies? The collective body of SEL implementation research, exemplified in the articles of this special issue and more broadly, addresses both academic (i.e., for the sake of increasing our generalizable knowledge) and utilitarian (i.e., for the practical advancement of the scaling of SEL practice in schools) ends. Though these are sometimes overlapping goals simultaneously advanced, for the sake of clarity and space, this commentary will primarily address the practical and pragmatic value and lessons of this special issue, with admittedly less attention paid to issues of methodology, analytic techniques, or study designs.Considering the lessons we can draw across these seven SEL implementation studies, we might start with the end in mind: what could we do if we arrived at a clear list of the most important predictors of high-(or low-)quality implementation? It is a herculean task to elucidate the characteristics of social-emotional development and subsequently use that knowledge to craft an intervention intende...