During June-July 2015, Public Health-Seattle & King County (PHSKC) and Washington State Department of Health (WADOH) investigated 22 clusters of Salmonella serotype I 4,[5], 12:i:- infections. Serotype I 4,[5], 12:i:- is the fifth most frequently reported Salmonella serotype in the United States, but is uncommon in Washington. On July 29, 2015, WADOH and PHSKC requested assistance from CDC to identify the infection source, determine risk factors, and make recommendations for prevention.