A project to overcome institutional constraints to breast-feeding was implemented in a large municipal hospital. Interventions included staff education, intensive training of a team of physicians and nurses, development of user-tested educational materials, and day and evening staffing by a breast-feeding counselor. A nearby hospital served as a control. Project evaluation entailed chart reviews at the intervention site and a control hospital (n = 812); interviews with mothers during their postpartum hospital stay and at return clinic visits (n = 180); and field observations in all areas of the hospital that provided prenatal, intrapartum, postpartum, and pediatric care. Comparisons of the incidence and pattern of breast-feeding were made before, midway through, and after the project. At the intervention site, the incidence of breast-feeding increased from 15% to 56%, and exclusive breast-feeding for more than 3/4 of feedings increased from 0% to 15%. At the control site, the respective changes were from 28% to 41% and from 5% to 7%. Formula use by breast-feeding women decreased but was nonetheless extensive, and the usual reason given by breast-feeding women for supplementation was a perceived insufficiency of breast milk. This may be due, in part, to the fact that bedside assistance to breast-feeding mothers was not integrated into the routine care provided by staff nurses but was relegated to the lactation nurse/counselors who were not available at all times. It is concluded that the process to overcome institutional constraints to breast-feeding is difficult but feasible. Repeated and extensive professional education helps create the context whereby clinical and administrative staff can reassess routines and policies.