This report describes the breastfeeding and weaning practices of rural women in two Mexican towns and the cultural beliefs upon which these practices are based. Interviews and focus group discussions were used to collect information. Women thought breastfeeding preferable to bottle-feeding. Eighty percent initiated breastfeeding and 69% gave colostrum. Breastfeeding was discontinued early (mean age 4 months). The mean age at which children were introduced to other liquids was 2 months (range 0-5 months) and to solids, 4 months (range 1-8 months). Women's decisions regarding infant feeding were influenced most by custom and advice from doctors and family members. In some instances medical advice conflicted with traditional practices. These findings suggest important avenues for intervention in hospital practices, education for health care workers, and in the development of health promotion services.