PROMISE—Promoting Readiness of Minors in Supplemental Security Income (SSI)—was a joint initiative of the U.S. Department of Education (ED), the Social Security Administration (SSA), the U.S. Department of Health and Human Services, and the U.S. Department of Labor to fund and evaluate programs to promote positive changes in the lives of youth who were receiving SSI and their families. Under cooperative agreements with ED, six entities across 11 states enrolled SSI youth ages 14 through 16 and implemented demonstration programs intended to (1) provide educational, vocational, and other services to youth and their families and (2) make better use of existing resources by improving service coordination among state and local agencies. Under contract to SSA, Mathematica Policy Research is evaluating how the programs were implemented and operated, their impacts on SSI payments and education and employment outcomes for youth and their families (using an experimental design under which we randomly assigned youth to treatment or control groups), and their cost-effectiveness. In this report, we present the plan for selecting the sample for and administering the PROMISE evaluation’s 60-month follow-up survey.