FSIS chose its Salmonella performance standards based on the assumption that a 30 percent reduction in the occurrence of Salmonella-contaminated chicken parts samples would result following the implementation of the performance-based standards program. The performance standards are based on FSIS slaughter establishment data and U.S. Food and Drug Administration (FDA) retail data that was collected prior to the implementation of the standards and in the intervening years. Overall changes in the Salmonella contamination of chicken parts were assessed and included in a historical review of how such changes relate to the performance standard.