A potential enteropathogen was found in 50% of 1219 diarrheal episodes and 48% of 511 asymptomatic controls in a 1-year community study of childhood diarrhea. Rotavirus (3% of episodes), Cryptosporidium species (6%), and enteropathogenic Escherichia coli (EPEC) with EPEC adherence factor (4%) were more prevalent in cases than controls. Giardia lamblia (19%) was the most prevalent organism but was not associated with diarrhea. Enterotoxigenic E. coli (12%), Strongyloides stercoralis (5%), Shigella species (2%), Entamoeba histolytica trophozoites (2%), and Vibrio cholerae (1%) were found at nonsignificantly higher rates. Salmonella and Campylobacter specieswere more prevalent among control infants. Cryptosporidium species and sequential infections from other pathogens caused persistent diarrhea.