While debates on migration policy often revolve around rival values and interests, they also invoke knowledge claims about the causes, dynamics and impacts of migration. Such claims are best conceptualised as policy narratives, setting out beliefs about policy problems and appropriate interventions. Narratives are likely to be more successful where they meet three criteria: they are cognitively plausible, dramatically or morally compelling and, importantly, they chime with perceived interests. Increasingly, such narratives are also expected to draw on expert knowledge, although knowledge is often deployed to legitimise particular actors or preferences rather than to enhance the cognitive plausibility of the narrative. The series of articles in this issue explore how narratives are developed, codified, revised and diffused in policy debates and policy-making. We hope that they contribute not just to understanding migration policy, but also to wider debates on the role of ideas and knowledge in public policy.