In recent years, strengthening marriages and relationships in low-income families has emerged as a national policy strategy to enhance child well-being. Mathematica recently conducted a study of how programs and services to strengthen relationships in unmarried parent families can be developed, implemented, and evaluated. The study culminated in a conceptual framework that identifies factors to consider in developing such programs, including the circumstances and needs of unwed parent families, program curricula, issues related to implementation and service delivery, and outcomes that should be affected. This brief focuses on the program design aspects of the conceptual framework. (Author abstract)