The Children’s Bureau, within the Administration for Children and Families (U.S. Department of Health and Human Services), funded a multiphase grant program to build the evidence base on what works to prevent homelessness among youth and young adults who have been involved in the child welfare system. Known as Youth At-Risk of Homelessness (YARH), this program funded 18 organizations for the first phase for two years. The authors conducted a process study, also known as an implementation study, to provide contextual data about challenges faced and decisions made by the grantees as they planned and implemented their programs. This report describes the Phase I process study that documented the activities and progress grantees made in the following areas: 1) managing the Phase I timeline, 2) building partnerships 3) using data, and 4) developing comprehensive service models. (author abstract modified)