The Birbhum HDSS was established in 2008 and covers 351 villages in four administrative blocks in rural areas of Birbhum district of West Bengal, India. The project currently follows 54 585 individuals living in 12 557 households. The population being followed up is economically underprivileged and socially marginalized. The HDSS, a prospective longitudinal cohort study, has been designed to study changes in population demographic, health and healthcare utilization. In addition to collecting data on vital statistics and antenatal and postnatal tracking, verbal autopsies are being performed. Moreover, periodic surveys capturing socio-demographic and economic conditions have been conducted twice. Data on nutritional status (children as well as adults), non-communicable diseases, smoking etc. have also been collected in special surveys. Currently, intervention studies on anaemia, undernutrition and common preschool childhood morbidities through behavioural changes are under way.