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Theorizing the Evolution of European Migration Systems (THEMIS) was a four-year project which took a fresh look at how patterns of migration to Europe develop, focusing on the conditions that encourage initial moves by pioneer migrants to become established migration systems (or not). Following the end of the project its data is now available to interested researchers through the UK Data Service [click through section to access link]

Led by IMI in partnership with Erasmus University Rotterdam, PRIO and the University of Lisbon, and funded by NORFACE, THEMIS took a fresh look at how patterns of migration to Europe develop, focusing on the conditions that encourage initial moves by pioneer migrants to become established migration systems (or not). It sought to bridge the theories on the initiation and continuation of migration, and to integrate the concept of agency in a systems theory approach.

It is sometimes suggested that migration patterns evolve following a trajectory where individuals start to move from one country to another, and over time, more people join them: once a critical mass is reached, that migration flow expands rapidly. However, there is not enough evidence to back up this theory of migration dynamics partly because studies to date have tended to focus either on the ‘root causes’ of migration or on the reasons why migration processes gain momentum and become established migration systems. A related issue is lack of theory to explain why many initial pioneer migration movements do not set in motion self-reinforcing migration dynamics. Current theories also fail to explain adequately the stagnation and weakening of established migration systems.

The THEMIS international project team investigated what makes people decide to migrate, why some of those initial moves to Europe result in the formation of significant migration systems, and why some migration processes simply tail off or stagnate. This involved a comparative study of the evolution of migrant groups following different migration trajectories from several regions of three origin countries (Brazil, Morocco and Ukraine ) to selected cities in four destination countries (UK, Norway, the Netherlands and Portugal).

Following the conclusion of the project in 2014 the project datasets and metadata have been deposited for secure archive in the UK Data Service. The data include surveys conducted in both areas of origin in Brazil, Morocco and Ukraine (total 1,246 respondents) and destinations in Norway, Portugal, the Netherlands and the UK (total 2,859 respondents).

The THEMIS project also gathered a large volume of qualitative data through over 630 semi-structured interviews. The interview guidelines were published but it has not been possible to make available the interviews, although the project team will consider requests from researchers who would like access to transcripts.

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If you draw on this information for your qualitative or quantitative research, please cite the material in the following way:

  • International Migration Institute, University of Oxford; Erasmus Universiteit Rotterdam; Instituto de Geografia e Ordenamento do Territorio da Universidade de Lisboa; Peace Research Institute Oslo. (2015). Theorizing the Evolution of European Migration Systems, 2010-2013: Special Licence Access. [data collection]. UK Data Service. SN: 7771,

Find out more about the THEMIS project, including its methodology and approach, research partners, and project publications.

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