Full text article. Also available at https://www.ajol.info/index.php/thrb/article/view/157688Undernutrition in children has remained a challenge despite the success achieved in reduction of other childhood diseases in Zanzibar. Most empirical studies on infants and young child feeding (IYCF) have examined nutritional value of foods fed to the children in terms of energy and micronutrient content. Little is known on the role of culture, traditions and social norms in influencing IYCF practices. This study aimed at assessing the existing IYCF practices and socio-cultural factors influencing these practises using ProPAN tool to get an in-depth understanding of the mothers practices with respect to exclusive breastfeeding and infant and young child feeding. A cross sectional study involving mothers/caregivers was conducted using semi-structured interviews and opportunistic observations on Unguja Island, Zanzibar. A random selection of 36 Shehias and 213 households with children 0 – 23 months old was done proportional-to-size of Shehias and children. Quantitative and qualitative data were collected using the ProPAN tool and embedded software for analyses. A total of 213 of mothers/caregivers were involved in the study. Almost all new-borns were fed colostrum (96%). Proportion of mothers who initiated breastfeeding within one hour after giving birth was 63%. About 24% of the women practiced exclusive breastfeeding and 21% of the children were given pre-lacteal feeds 2-3 days after birth. The mean age of introduction of complementary foods was four months. Responsive feeding was not practiced by some mothers as 31% of the children 12-23 months of age were left to eat alone without any support from caregivers. The common reasons for non-adherence to the recommended feeding practices were related to income and socio-cultural norms which are strong in the community and supported by other family members. Infant and young child feeding in Unguja was suboptimal. Inadequate care practices, use of pre-lacteals, early introduction of complementary foods, low rate of exclusive breastfeeding and low meal frequency were among the common practices. The main causes of the observed feeding practice were related to socio-cultural norms and beliefs. There is a need to strengthen IYCF education into the antenatal clinic regime.