A small-scale, prospective study of breastfeeding and weaning practices was conducted in a seminomadic pastoral population in northern Tanzania (Datoga of Mbulu District, Arusha Region). Focus group participants suggested that weaning patterns are strongly influenced by seasonal factors, and individual mothers often stated an intention to introduce adult staple foods and terminate breastfeeding at the end of the long rains. However, a combination of maternal self-perception, assessment of infant well-being, and indicators of household food supply influenced the actual progression of weaning for individual children. The results suggest that interventions to promote exclusive breastfeeding and improve complementary feeding practices in rural East African pastoral populations could build on maternal attention to infant-centered cues and address household-level constraints on caregivers making decisions about young child feeding.