In the financial capability intervention known as Child Development Accounts (CDAs), incentives with savings or investment accounts enable families (especially vulnerable ones) to accumulate assets for children's developmental and life‐cycle needs. With data from SEED for Oklahoma Kids (OK), a randomized statewide policy experiment, we examined a CDA intervention's effects on a subsample of low‐income families in Temporary Assistance for Needy Families and Head Start. Results from simultaneous equation modeling suggest that the intervention has positive, statistically significant impacts on financial and social‐development outcomes. Findings provide empirical support for a new model for integrating the accounts with other social services for economically vulnerable populations. The centralized account platform used in SEED OK seems essential to providing CDAs on a large scale, which would enable opportunities for integration with federal‐ and state‐funded social service programs.