Transmission of Shigella sonnei had been documented in a rural Alaskan community at least one month before a potlatch was held. An outbreak developed associated with participation at the potlatch. A large batch of mouse soup was prepared and was served over multiple days. Those who consumed moose soup were at increased risk for becoming ill with Shigella sonnei. The risk of illness increased as people ate additional servings of soup. A food preparer likely contaminated the soup. Temperature control problems may have promoted bacterial growth.