Breast-feeding and weaning practices were observed for a cohort of 81 children under 3 years of age in the context of a longitudinal study of social, ecological and nutritional factors affecting growth in a semi-nomadic population of pastoralists in northern Tanzania (WaDatoga of Mbulu District). The adequacy of indigenous infant and young child feeding practices was assessed in relation to current international recommendations. Objectives were to provide baseline data for future investigations of any changes in young child feeding practices which accompany population shifts towards settlement and non-pastoral modes of subsistence, and to improve understanding of the strengths and limitations of indigenous feeding practices in this type of population. It was found that while breast-feeding was universally initiated, other aspects of young child feeding practices do not meet current international recommendations. Prelacteal feeds are commonly used, supplementary feeding with non-human milks usually occurs before 4 months of age, use of solid foods normally begins later than 6 months, and breast-feeding does not continue until 2 years of age for the majority of children. The data have implications for the design of breast-feeding promotion and improved weaning food interventions among African pastoralists.