This special issue illustrates that the securitisation of migration is not a linear process but a spiralling phenomenon, which involves different actors, and their policies, practices and narratives, in a spiralling progression that both self-fulfils and reinforces migration-security nexus’ dynamics. By proposing a cognitive ontology to understand the social construction of migration as a security threat, the introduction to this special issue proposes a categorisation of cognitions, mandates, constituencies and interests of state and non-state actors. Through a dichotomisation of these categories, it is possible to clarify how and why they either socially construct or deconstruct migration as a threat. In particular, the special issue identifies in prejudicial cognitions one of the main reasons for which a variety of actors enact practices and produce narratives that contribute to both securitising migration and reinforcing its nexus with crime, and the consequent social construction of ‘migration crises’. The different contributions to this special issue prove the arguments here exposed with a different analysis of how migration has been dealt with at either governmental or non-governmental levels.