In November 2012, Minnesota Department of Health staff investigated an outbreak of norovirus associated with consumption of food served at a birthday party. The complaint group had several common exposures during the incubation period. As a result, neither a vehicle nor the source of contamination was identified. However, based on the distribution of incubations, the exposure most likely occurred on November 24 at a restaurant or a bakery. Four party attendees met the outbreak case definition. No one was hospitalized and no one died. One stool specimen was positive for norovirus GII.