Epidemiologic, laboratory, and traceback investigations conducted by local, state, and federal officials indicate that consumption of Foster Farms brand chicken is the likely source of this outbreak of Salmonella Heidelberg infections. A total of 416 individuals infected with the outbreak strains of Salmonella Heidelberg have been reported from 23 states and Puerto Rico. Most of the ill persons (74%) have been reported from California. The number of ill persons identified in each state is as follows: Alaska (1), Arkansas (1), Arizona (18), California (310), Colorado (9), Connecticut (1), Delaware (1), Florida (4), Idaho (4), Illinois (1), Kentucky (1), Louisiana (1), Michigan (3), Missouri (5), North Carolina (1), Nevada (10), New Mexico (2), Oregon (10), Puerto Rico (1), Texas (10), Utah (2), Virginia (3), Washington (16), and Wisconsin (1).