An outbreak of what was likely a viral gastroenteritis occurred among persons who attended a wedding reception in Campbell County, Wyoming. The event was held at a local banquet facility and was catered by a local restaurant. The wedding cake was made by a local cake-maker in her home. Based on statistical analysis it appeared that cake, potato salad, lemonade, and watermelon were the four food items most strongly associated with illness. Five of six employees of the catering restaurant and the cake-maker were interviewed. All of them denied gastrointestinal illness at the time of the reception or in the preceding month. A stool specimen obtained from one of the cases tested negative for bacterial pathogens and negative for Norovirus. Another case patient was admitted to the local hospital during his illness. A stool culture obtained during that time was negative for bacterial pathogens. Available food samples tested negative for Norovirus. The clinical and epidemiologic characteristics of this outbreak were suggestive of viral gastroenteritis, but the specific virus was never identified.