The Ballabgarh Health and Demographic Surveillance System (HDSS), also known as the Comprehensive Rural Health Services Project (CRHSP) Ballabgarh, is located in north India and was established in 1961 to develop a model for rural health-care practice in India. In addition to demographic surveillance and communitybased research, CRHSP Ballabgarh provides preventive, health-promotion, and curative services to its surrounding population. The population served by CRHSP Ballabgarh in 2011 was about 90 000. The system collects data for the entire population through fortnightly visits by health workers (HWs). The system’s data base is updated once every month and further updated with missing data and special morbidity surveillance data during the annual census. Since 1961, CRHSP Ballabgarh has collected demographic data, reproductive data, and health data about mothers and their children. More recently, the project began collecting data on diseases such as tuberculosis, and because of changes in life style it recently began collecting data about non-communicable diseases (NCD) and risk factors for NCDs. Nonetheless, an adverse sex ratio, with more boys than girls, and a stagnant neonatal mortality rate, remain major challenges in the population served by CRHSP Ballabgarh. The project shares data with different agencies for health-management purposes, which can be made available to bona fide researchers on receipt of a proposal (enquiries should be directed to: email@example.com); collaboration requests are welcome.