An outbreak of Campylobacter jejuni occurred among persons who attended school luncheons in Kansas on September 14 or 15. The cohort study showed that the consumption of gravy or pineapple were significantly associated with illness. A food worker at the luncheon had severe diarrhea on the day of the luncheon and was the likely source of the outbreak. Pulsed field gel electrophoresis, a genetic fingerprinting technique, had been used for the first time to differentiate cases associated with the luncheon versus other cases that occurred in the broader community.