This paper reports the results of a survey of socio-economic background and the academic performance of undergraduates at the University of Kelaniya in Sri Lanka. Socio-economic background of entrants differed significantly between the science and arts streams. Students in the faculty of science were more likely to be from the urban-affluent families whereas the students in the faculty of arts were more likely to be from the rural-low-income families. A significant variation in academic performance between male and female students was observed only among the science stream. No significant associations between socio-economic indicators such as place of residence while attending university, family size, level of education of parents, living standard at home, family income, university education in the family, and rank order in family and examination performance were found.