Until recently, federal programs had not explicitly focused on improving the outcomes of highly vulnerable teen parents. Established in 2010, the Pregnancy Assistance Fund (PAF) aims to improve the health, social, educational, and economic outcomes for expectant and parenting teens and young adults, their children, and their families, through providing grants to states and tribes. This article introduces the Maternal and Child Health Journal supplement “Supporting Expectant and Parenting Teens: The Pregnancy Assistance Fund,” which draws together the perspectives of researchers and practitioners to provide insights into serving expectant and parenting teens through the PAF program. The articles in the supplement include examples of programs that use different intervention strategies to support teen parents, with programs based in high school, college, and community settings in both urban and rural locations. Some of the articles provide rigorous evidence of what works to support teen parents. In addition, the articles demonstrate key lessons learned from implementation, including allowing some flexibility in implementation while clearly outlining core programmatic components, using partnerships to meet the multifaceted needs of young parents, hiring the right staff and providing extensive training, using strategies for engaging and recruiting teen parents, and planning for sustainability early. The studies use a range of qualitative and quantitative methods to evaluate programs to support teen parents, and three articles describe how to implement innovative and cost effective methods to evaluate these kinds of programs. By summarizing findings across the supplement, we increase understanding of what is known about serving expectant and parenting teens and point to next steps for future research.