Introduction to special section: Federally funded, community-based healthy marriage and responsible fatherhood program impact studies.

The focus of this special section is impact studies that were conducted as part of the Administration for Children and Families' Healthy Marriage and Responsible Fatherhood initiative. This initiative has led to more than 2 million people receiving relationship education and fatherhood programs across the United States over the last two decades. Community organizations develop these programs, select their curricula and content, and run these programs in their local communities. Many programs funded in the 2015-2020 cohort of grantees included randomized controlled trials of program effectiveness; some of these studies are presented in this issue, with the goal of marrying the field of program evaluation and family science.