Mathematica and its research partners in Kenya, Tanzania, and Mozambique (The ECD Network for Kenya, Ifakara Health Institute, and KixiQuila Consultores, respectively) worked together with ECD stakeholders to conduct systems mapping and a first-of-its-kind systems diagnostic. This report provides systems maps that visualize the relationships among each country’s systems actors, identifies both global and country-specific barriers and facilitators to systems change, and proposes potential strategies to strengthen multisectoral cooperation governance, policies, and financing structures in support of high-quality, sustainable early childhood services for all.