From the building of walls and fences to the creation of hostile environments for outsiders, few governments have held out a welcome for immigrants. Yet, as emerging labour shortages are showing, migrants are needed, if not wanted. The reasons for the shortages are not in themselves simply the result of anti-migration policy, but the importation of migrant workers is part of the policy response, particularly if that importation can be seen to be temporary: that migrants will be allowed into a country only to achieve very specific and limited tasks and will go home after those have been achieved. This brief entry first examines issues of terminology and definition, then goes on to consider the more conceptual aspects of the policy before examining a few specific cases of circular migration and coming to a conclusion.