This article gives a brief history of immigration into Britain this century as an introduction to a description of the size and main characteristics of the different ethnic minority populations living in Britain today. Using data from the 1991 Census-the first to include a question on ethnic group-the article covers the demographic background and main features of Britain's present-day ethnic minority populations and provides an introduction to the wealth of analyses which has followed the release of ethnicity data from the 1991 Census.