Definitions of both mental health and migration are ambiguous and contested, and any attempt to integrate the two phenomena is fraught with the challenge of comprehending and interpreting such constantly moving targets. The difficulties are not confined to changes over time and space, but involve many different understandings of the criteria for "normality" and multiple perceptions of migration. Nevertheless, there is sufficient evidence of a perceived link between migration and mental illness to warrant a multidisciplinary evaluation, blending conceptual and empirical models and covering a broad chronological, spatial and thematic spectrum.