Each month, the Commodity Supplemental Food Program (CSFP) provides supplemental food packages to half a million women, children and seniors. This study looks at how CSFP operates, who participates, and how it fits into the overall food assistance landscape. It estimates that 2.9 million mothers, infants, and children meet eligibility requirements for CSFP but not for WIC. About 7.5 million seniors would be eligible if CSFP were available everywhere. In states where the program is widely available, more seniors participate in CSFP than in the Food Stamp Program. Use of volunteers, staff stability, and the small scale of operations contribute to CSFPs simplicity and accessibility.