The Food Stamp Program (FSP) helps low-income individuals purchase food so that they can obtain a nutritious diet. The number of eligible individuals served in an average month by the FSP increased from 16.9 million in 2001 to 18.7 million participants in 2002, an increase of over 10 percent. Most individuals are eligible for the program if their financial resources fall below certain income and asset thresholds. Not all of those who are eligible participate in the program, however. Some choose not to participate, while others are unaware that they are eligible. The food stamp participation rate — the percentage of eligible people who actually participate in the FSP — is an important measure of how well the program is reaching its target population. This report presents estimated participation rates for 2002 and revised estimates of rates for 1999, 2000, and 2001.