Campylobacter jejuni is a major cause of diarrhea among children in developing countries. Since free-ranging chickens are a major source of Campylobacter infections, we hypothesized that corralling of these chickens would result in decreased rates of Campylobacter infections and Campylobacter-related diarrhea. We tested this hypothesis in Peruvian families in a periruban shantytown with free-ranging chickens and randomized by household using a (corralling) intervention versus control study design. Samples from participants and chickens were cultured for Campylobacter at the start of surveillance, and samples from children less than six years of age with diarrhea episodes and two sentinel chickens were cultured for Campylobacter monthly. Overall, 4,257 human stool specimens and 3,950 avian stool specimens were cultured over a 17-month period. Rates of Campylobacter-related diarrhea in children were significantly higher in the corral group, which demonstrated twice the incidence of Campylobacter diarrhea compared with controls overall, and seven times the rate of Campylobacter diarrhea versus controls in the subset with more than 20 household chickens. Rates of asymptomatic infection with Campylobacter were similar. Although corralling may be useful if corrals are distant from living quarters, it is not advisable as a control measure for Campylobacter in communities such as this. Copyright © 2006 by The American Society of Tropical Medicine and Hygiene.