A large family reunion in Marion County, Kansas had a catered meal that resulted in an outbreak of Norovirus. One of the family members notified the health department that around one hundred family members in nine states were reporting illness. The investigation began with a cohort study of the family members' food histories. This study found potato salad significantly associated with illness. Stool samples from a select number of case-patients tested positive for Norovirus confirming the etiology of the illnesses. An environmental inspection of the catering company found three critical violations: unclean food equipment, an unlabled chemical spray bottle, and a cold holding violation. No food handlers reported being ill, but asymptomatic shedding of the virus is not uncommon.