In this introduction, we outline the most relevant concepts for this special issue on integration and the politics of difference. This introduction characterizes "integration" as a dominant policy orientation and discursive regime concerned primarily with understandings of language, communication, and skill which constitute a (trans)national politics of difference. In various sites and national contexts of the global north, migrant "integration" policies render difference and mobility the site of both discursive elaboration and management. This introduction highlights the salience of critical ethnographic analyses for understanding "integration" beyond policy realms, arguing for attention to situated practices, emergent social categories and types, political-economic stakes, logics of linguistic (dis)engagement, and the reproduction of mono- and multilingual social orders. In particular, we propose to untangle this complex by describing three central processes that run through all of the contributions and which, we suggest, are indispensable for the analysis of current and emergent regimes of integration: processes of categorization, of selection, and of activation.