The Behavioral Interventions to Advance Self-Sufficiency (BIAS) project is the first major opportunity to use a behavioral economics lens to look at programs that serve poor and vulnerable people in the United States. Sponsored by the Office of Planning, Research and Evaluation of the Administration for Children and Families (ACF) within the U.S. Department of Health and Human Services, the BIAS project aims to learn how tools from behavioral economics can improve the well-being of individuals and families served by programs that ACF supports. Many human services programs require clients to make active decisions and follow a series of steps in order to reap a benefit — from deciding to apply, to completing forms, to arranging for child care. Program designers often assume that individuals will carefully consider options, make decisions that maximize their well-being, and diligently follow through. Behavioral economics, which combines insights from psychology and economics, may help explain why these assumptions are not always borne out.