Theories to explain internal migration in advanced industrial countries have largely failed to get to grips with two fundamental and interrelated phenomena: the organisation of employment and the development of internal labour markets by employers. Most explanations either rely on models based on broad economic forces or on the behaviour of migrants using supply side information from social surveys. Only two major studies exist, the Organisational Labour Migration Study and the more study carried out by the Institute of Manpower Studies. Corporate transfer is a response to a range of situations. All large organisations transfer staff on a recurrent basis as part of career development. Other important causes are rationalisation, consequent upon changed trading conditions and the need to move staff from closing or declining locations; and expansion, where developments in new locations require inputs of experienced employees. Explaining relocation of staff within corporate labour markets requires an approach different from that adopted in most studies of migration.