This paper analyses the role of migration in residential social change in London during the intercensal decade 1971-81 using data from the 1 % Longitudinal Survey. It compares the socio-economic composition of out-migrants from, and in-migrants to London with the changing socio-economic composition of continuing residents, and it assesses the relative importance of migration and in-situ social change. It shows that while the incidence of out-migration of professional and managerial workers from London is high, this is partly offset by high levels of inmigration into these groups, especially among young people who were economically inactive in 1971 but who were classed as managers or professional workers in 1981. There is also a high level o...