Understanding the impact of preemptive interventions on development for those with a high likelihood for autism is a critical step in building a transdiagnostic model of optimized intervention. The purpose of this systematic review and meta-analysis is to examine the impact of preemptive autism interventions on parent outcomes and child developmental outcomes. A total of 345 unique records were assessed for eligibility yielding 13 unique studies with 715 total infant/toddlers with a high likelihood for autism. There was a significant association between the early interventions on parent implementation of intervention strategies immediately following the intervention. However, there was no significant association between the early interventions and child developmental outcomes. The studies reporting moderator and/or mediator analyses suggest a meaningful association between parent implementation and long-term child social communication outcomes. Taken together, these findings suggest that parent-mediated interventions are associated with improved parent use of strategies, and although these results do not translate into immediate or short-term child developmental outcomes, there is evidence that parents with the greatest implementation facilitate later improved communication outcomes for their children. There is an urgent need to develop a nuanced intervention approach during a time of ever-changing concern about child development.