The Food Stamp Program (FSP) is the largest of domestic food and nutrition assistance programs administered by the U.S. Department of Agriculture's Food and Nutrition Services (FNS). During fiscal year 2000, the FSP served and average of 17.2 million persons per month, paying out almost $15.0 billion in food stamps throughout the year. The characteristics of food stamp households and the level of FSP participation change over time in response to economic and demographic trends, and to legislative changes in eligibility requirements. To track these changes and measure their effect on the FSP, FNS relies on data from the QC database, which is an edited version of the FSP Quality Control (FSPQC) database. The FSPQC database contains detailed demographic, economic, and FSP eligibility information for a nationally representative sample of 46,963 FSP units. The FSPQC data are generated from monthly quality control (QC) reviews of FSP cases that are conducted by state FSP agencies to assess the accuracy of eligibility determinations and benefit calculations for the state's FSP caseload. These data, which are produced annually, are ideal for tabulations of the characteristics of food stamp units and for simulating the impact of various reforms to the FSP on current FSP sites.