Numerous evidence-based programs (EBPs) exist for delivery in schools to promote youth mental health outcomes. However, school systems often lack the internal infrastructure to support the effective implementation and sustainment of EBPs when external supports are withdrawn, resulting in notable attenuation in the benefits in youth clinical outcomes that are associated with EBPs. This paper illustrates how to leverage concepts from improvement science and implementation science to develop learning school systems dedicated to enhancing the infrastructure capacity of a school to advance the implementation and sustainment of EBPs. In particular, we discuss how treatment integrity (extent to which an EBP is delivered as designed) and youth mental health outcome data are: (1) collected; (2) analyzed and interpreted; and (3) fed back into the school system to increase organizational supports and promote school practitioners' behavior change to produce improvements in youth mental health outcomes. We also discuss psychological safety among the people within a school system as a key characteristic of a learning school system. We then present a theory-informed approach to learning school systems to demonstrate how data generated by a learning school system can lead to precise and effective plans that continuously improve implementation and result in the eventual sustainment of EBPs. We conclude with a brief research agenda with concrete steps toward realizing the potential of learning school systems to support the implementation and sustainment of EBPs for mental health problems.