In January 2016 an outbreak of gastrointestinal illness occurred among patrons of New Theatre Restaurant located in Overland Park, Kansas. Dates of onset of illness ranged from January 14 to January 31. Two etiologic agents were identified. Initially, norovirus was confirmed in patients but during the investigation, an outbreak of Clostridium perfringens infections was also detected. Six hundred thirty six persons became ill with norovirus. Three people were hospitalized. No one died. Ten persons reported gastrointestinal symptoms consistent with norovirus before attending the dinner theater and one employee reported onset of symptoms while at work. Fifty-five persons reported gastrointestinal symptoms consistent with Clostridium perfringens. One stool specimen tested positive for Clostridium perfringens enterotoxin type A.