An outbreak of Salmonellosis occurred among students and employees of a small school district in Oklahoma, involving four schools. Salmonella Heidelberg and Salmonella Stanley were isolated from stool samples of some of the case-patients. Illness was strongly associated with eating chicken from the school cafeteria on April 2. No other foods were implicated. The food served at the four schools was prepared at one location. Frozen chicken was left to thaw at room temperature. The following day, the chicken was baked for two hours at 350 F. The oven was turned off, and the chicken was left overnight in the cooling oven. Other chicken was cooked for two hours in a steam cooker and then left in the device overnight at the lowest possible setting. Cafeteria workers became ill subsequent to the April 2 cafeteria meals. Cafeteria workers had received little training and apparently had little understanding of proper cooking or temperature control.