The current paper provides an update of the IECMHC evidence base. Included studies (n = 16) were systematically gathered, screened, and coded for context, intervention characteristics, methods and measures, outcomes across ecological levels, and alignment with the IDEAS Impact Framework's guiding questions. Our analysis replicates prior reviews, describing the positive impact of IECMHC on outcomes such as child externalizing behavior, teacher self-efficacy, and teacher-child interactions. Beyond updating prior reviews, this analysis describes emerging, nuanced findings regarding the mechanisms of change and the differential impact of IECMHC. We augment our review with descriptions of evaluations that did not meet our inclusion criteria (e.g., IECMHC in the home visiting context, unpublished evaluation reports) to provide context for our findings. Finally, we provide policy and practice implications and articulate an agenda for future research. (author abstract)