Parenting is widely considered to be among the most important influences on early childhood (EC) development. But to what extent and under what circumstances can EC parenting programs improve child learning outcomes? While substantial progress has been made toward addressing these questions in recent years, there have been few attempts to systematically synthesize the evidence thus far with a view toward scaling and policy implications. This paper works toward filling this gap through a systematic review including both a quantitative meta-analysis and a detailed narrative analysis of randomized evaluations that test the impacts of EC parenting programs on learning outcomes. We find that these programs generate substantial effects across a wide range of contexts, and that the largest impacts are associated with programs that are conducted in low- or middle-income countries and that use curricula focusing on cognitive stimulation. Group parenting programs tend to yield effect sizes that are, on average, comparable to home visiting programs, typically at substantially lower costs. Qualitative analysis of evaluations of scaled interventions reveals that administrative implementation barriers rather than program ineffectiveness likely represent the primary impediment to stronger impact. We conclude by reflecting on implications for theory, policy, and priorities for future research.