The Department of Demography, University of Colombo began its activities in 1997 as an  upgraded form of the Demographic Training and Research Unit (DTRU),  which was established within the faculty of Arts of the then Colombo Campus of the University of Sri Lanka, with the assistance of the United Nations Fund for Population Activities (currently, UNFPA) in 1973.  The Department serves as the sole academic body of Sri Lanka in providing undergraduate and postgraduate level teaching, undertaking research, and training in Demography and Population Studies. At present, on average, more than 1000 students follow courses in Demography at both undergraduate and postgraduate levels. In addition, the staffs of the Department extend their academic, research and training activities to poster other fields of natural science and social sciences such as Medical science, Statistics, Town and Country Planning, Sociology, Economics, Geography and Environmental science, etc.  The  staff engage in teaching and research in wider areas such as, , Fertility and Mortality dynamics, Internal and International Migration, Sexual and reproductive health, Population Dynamics and Family planning, Population and Health, Labour Force and Economic Demography, Social Demography, Family Demography, Population and environment, Population and Development etc. At the national level the academic members engaged in training personnel in the field of population studies, and also provide consultancy services to the government departments, ministries, and national and international organizations