In August 2017 Public Health Seattle King County (PHSKC) staff learned of two individuals with lab-confirmed Campylobacter who had attended the same private party on June 24, 2017. Each case reported multiple other ill persons associated with the same party. None of the other ill persons was interviewed to confirm illness details. Food for the party was prepared in a private home and included chicken, a food item known to be associated with Campylobacter. However, chicken was purchased pre-cooked and was cooked a second time. No single food item was identified as the definitive source of illness.