Hospital interventions in support of breastfeeding have been highly successful in areas where the indigenous population has a well established environment of breastfeeding. However, programmes designed to improve breastfeeding patterns in urban populations have met with mixed success. This paper presents a prospective intervention study with a control group in which a health system-based breastfeeding promotion programme was initiated to support optimal breastfeeding for both child health and child spacing. Following collection of control data, a four-step intervention programme (Breastfeeding Promotion Program) was instituted. This paper reports the process of the development of the intervention programme as well as the comparison of the control and study populations. Major findings include significant increases in duration of full breastfeeding from 31.6 per cent at 6 months in the control group to 66.8 per cent in the intervention group. The duration of lactational amenorrhea was similarly increased: 22 per cent of the control mothers and 56 per cent of the intervention group women were in amenorrhoea at 180 days. The cost-effectiveness of the hospital changes is illustrated.