Monitoring integration sounds like a straight-forward process of measuring immigrants’ participation, behaviours, or attitudes. These measurements are meant to answer one deceptively simple question: “is an immigrant integrated?” The scientific literature on integration suggests that it is impossible to know whether or not any single person is integrated. When searching for a definition of integration, academics tend to treat the concept as a catch-all buzz-word for the two-way, multi-dimensional, long-term and non-linear processes of immigrant settlement (usually called immigrant integration) and social inclusion in increasingly diverse societies (often called societal integration). Inequalities increase and decrease over time between different individuals and groups and between different societies. These processes lie at the intersection of many policies, personal and societal factors and of divergent policy realms, uncoordinated bureaucratic structures, and contradictory public attitudes. There is no homogenous immigrant or native population, no uniform integration process, and no prevailing understanding of the impact of policies on these processes.