Contemporary international migration is characterized by increasingly complex migration patterns, with high shares of re-migration, i.e., return and onward migration after an initial move. Re-migration not only constitutes a significant part of net migration, but also has long-term consequences on the demographic and socio-economic composition of receiving countries’ foreign-born populations. Moreover, return migrants are considered to be important actors in sending countries' economic, social and political development. At the same time, return is used as a means of an increasingly restrictive migration policy, for example within the EU. In this dissertation, international re-migration is examined in terms of its scope, geographical patterns, underlying factors, individual decision-making processes and consequences. It consists of an introductory chapter, followed by four individual studies.

Study I examines patterns and determinants of return and onward migration among foreign-born individuals, using Swedish register data. The study analyses the importance of migration history, and social and economic attachments to Sweden. Although return migration is found to be the main form of remigration, onward migration is more prominent among specific migrant groups such as forced migrants. Whilst sharing many similarities, main differences between return and onward migration are related to age and the time spent in Sweden.

Study II assesses the potential bias in estimating the size of different migrant populations due to over-coverage in population registers. The results confirm the existence of over-coverage and the substantial bias in mortality and fertility rates for people of migrating age, due to over-coverage. Accounting for over-coverage is particularly important for correctly estimating migrant fertility, as the bias occurs mainly at the most common ages for migration and having children.

Study III examines the extent to which individual re-migration intentions might predict actual behaviour, compare their main determinants, and analyse what factors are related to the realization (or not) of re-migration intentions. Using a unique linkage of Swedish survey and register data, the study finds intention to be a relatively poor proxy of re-migration behaviour. Sharing many similarities, origin country ties are more related to re-migration intentions. Realizing intentions of both staying and leaving the destination country is found hindered by unemployment and economic difficulties.

Study IV examines conditions of voluntariness in international return migration and its relation to risks of experiencing economic difficulties post return, relying on rich survey data among Senegalese and Romanian returnees. Whilst emphasizing the complexity of voluntariness, the findings show that semi-involuntary returns are associated with higher risks of economic difficulties. Compared to non-migrants, migrant returnees do not necessarily experience lower risks of economic difficulties. For example, deported returnees to Senegal do not experience migration-related advantages.

Through its four studies, the dissertation addresses both conceptual and methodological challenges, which are constantly recurring in international migration research. The main results of the dissertation help to distinguish, compare and nuance the implications of traditional dichotomies in migration research, such as return vs. onward migration, intentions vs. behaviour, and deportation vs. "voluntary" return.