This article reviews the implementation of the community component of the Integrated Management of Childhood Illness (IMCI) strategy in Chao, Peru (2001 to 2004) and San Luis, Honduras (2003 to 2005). An evaluation was conducted in 2005 and included a project documentation review, key-informant interviews, and a household level baseline and follow-up survey of the WHO/UNICEF key family practices in each intervention site. The promotion of the key family practices in Chao and San Luís demonstrated measurable success. In comparison with the initial survey in 2002, the percentage of participant mothers ( N = 78) in Chao in 2004 who knew that they should breastfeed exclusively for at least six months increased from 33% to 94%; the presentation of complete vaccination records for one-year-old children increased by 19%; the recognition of danger signs for pneumonia increased 18% and for diarrhea by 8%; and the percentage of mothers who received four or more prenatal check-ups increased by 25%. A dramatic reduction in malaria cases was also attributed to the intervention in Chao. In San Luis, a quasi-experimental, random household sample ( N = 300) showed that the incidence of diarrheal disease among children under five years old declined by 18% between survey rounds (from 44% in August 2004 to 26% in December 2005). Social mobilization has promoted inter-sector consensus-building around community health issues, especially those related to maternal and child health. The promotion of the participation of representatives from various organizations via the community IMCI social-actor methodology has led to increased civic cooperation. Positive changes in health behaviors have been documented through an increase in preventive health practices, greater demand for primary health care services, and concrete community actions to improve public health.