Six persons who attended a baby shower in Seattle, Washington, developed fever and diarrhea. One of these illnesses was confirmed as caused by an antibiotic resistant, Shigella sonnei. A cohort study implicated the commercially distributed, ready-to-eat, 5-layer bean dip that was produced by Senor Felix. The product had been purchased at Costco Wholesale Club (Costco). After receiving a complaint from one of the ill persons, Costco notified its outlets. The San Diego, California, Costco had heard that the San Diego Health Department was investigating four foodborne outbreaks due to Shigella sonnei. The FDA was notified and a warning about the product was immediately issued. Additional case finding was conducted. Cases were subsequently identified in several states. Genetic fingerprinting of the Shigella isolated from ill persons and from product samples were indistinguishable. Numerous problems in manufacturing practices were noted at the dip-production facility. An ill employee who broke up the cheese by hand might have been a source for the Shigella, however Shigella was never isolated from his stool. There was a possibility that this outbreak was produce related. Several outbreaks of Shigella have been attributed in the past to fresh produce. The strain associated with this outbreak was implicated in a parsley-associated outbreak of Shigella sonnei in 1998. The salsa contained parsley.