From OPRE: The Behavioral Interventions to Advance Self-Sufficiency (BIAS) project is the first major effort to apply a behavioral economics lens to programs that serve poor and vulnerable families in the United States. This report presents findings from a behavioral intervention designed to increase the number of incarcerated noncustodial parents in Texas who apply for modifications to reduce the amount of their child support orders. Using a method called “behavioral diagnosis and design” the program redesigned the mailings informing these parents of the option to apply for an order modification. The redesigned materials resulted in a significant increase in applications at relatively low cost and demonstrated the promise of applying behavioral economics principles to improve program implementation and outcomes.