Psychosocial factors influencing behaviour play a central role in health research but seem under-explored in migration research. This is unfortunate because these factors, which include knowledge, attitudes, beliefs, intentions and personality traits, provide essential and potentially effective handles for linking migration and migrant-integration policies. We demonstrate that the health belief model (HBM) conceptualization of behavioural intentions contributes constructs that can further our understanding of migration intentions, thereby broadening the foundations for migration policies. We adapt the HBM to migration behaviour and then test it empirically by using survey data on international migration from West Africa and the Mediterranean region to the European Union. The results confirm that indicators of “perceived threat to living conditions”, “perceived benefits” and “perceived barriers to migration”, “cues to action” and “self-efficacy” contribute considerably to the explanation of migration intentions. We conclude that psychosocial factors deserve greater prominence in migration theories and empirical research, and we recommend that migration surveys consider this framework to identify relevant indicators of psychosocial factors of international migration and develop appropriate survey questions to measure them.