The Food Stamp Program (FSP) helps needy families purchase food so that they can maintain a nutritious diet. Families are eligible for the program if their financial resources fall below certain income and asset thresholds. However, not all eligible families participate in the program. Some choose not to, while others do not know they are eligible. The participation rate—the ratio of the number of participants to the number of eligibles—reveals the degree to which eligible families participate. This report concentrates on trends in the participation rates since 1994. It focuses on trends in the rates before and after welfare reform, and throughout much of the economic expansion of the 1990s.