Implementation science has grown considerably in school mental health over the past decade, driven by the persistent gaps between knowledge about "what works" to promote student well-being and what is typically delivered in schools. In 2014, Owens and colleagues outlined an implementation research agenda for the field of school mental health, emphasizing professional development and coaching, evidence-based practice fidelity, and sustainment. This paper provides a 10-year progress review across these domains and articulates an updated research agenda focused on: (1) pragmatic implementation strategies, (2) implementation mechanisms explaining the connection between implementation strategies and outcomes, (3) strategic intervention redesign to promote implementation, and (4) de-implementation of low-value practices. We propose critical research questions in these areas and conclude by highlighting contemporary study designs and methods (i.e., hybrid trial designs; sequential, multiple assignment, randomized trials; rapid qualitative approaches; economic analyses) that can be leveraged to investigate implementation research questions in school mental health over the next decade. In doing so, we hope to promote shared understanding of evolving implementation research priorities and opportunities to promote equitable, pragmatic, and sustainable implementation efforts in school mental health and drive synergy across projects.