An outbreak of Streptococcus occurred among guests of a party in a private home in Puerto Rico. The outbreak was suspected to be foodborne due to the high illness attack rate. Eating carrucho, a conch salad, was significantly associated with risk of illness. There were people who became ill after eating leftover carrucho without having been in attendance at the party. The carrucho had been prepared by a restaurant in San Juan. The conch used to make the carrucho came in a torn, unlabeled, plastic bag and was allegedly imported from Santo Domingo, Dominican Republic. None of the uncooked conch remained for testing, but the method of salad preparation should have been sufficient to kill streptococci bacteria. The food handlers and the food at the restaurant were cultured, and there was no evidence of streptococcus. The carrucho had been made in the afternoon of the day of the party. After purchasing the carrucho, the host of the party kept it in his automobile, unrefrigerated, for three hours.