The Quarterly Food-at-Home Price Database (QFAHPD) was developed to provide market-level food prices that can be used to study how prices affect food choices, intake, and health outcomes. This report presents a detailed description of the methodology used to construct the QFAHPD. The database, constructed from 1999-2006 Nielsen Homescan data, includes quarterly observations on the mean price of 52 food categories for 35 market groups covering the contiguous United States. Data from 2006 indicate that cross-market price variation can be as much as three to four times greater than annual food price inflation.