Over the past five decades, Sweden—and Malmö in particular—has undergone extensive demographic change driven by sustained immigration, resulting in increasing diversity and, in Malmö, a context in which people without a migration background now constitute a numerical minority. This transformation has generated a level of demographic complexity that is best captured by the concept of superdiversity, which emphasizes variation within groups and the interaction of multiple social, legal, and socioeconomic variables in shaping inequality, stratification, and belonging. Understanding these processes depends critically on data. While Sweden’s population registers provide unparalleled longitudinal coverage of socioeconomic outcomes, they cannot capture subjective identities, lived experiences, or intersecting forms of discrimination. The Diversity and Inclusion Survey makes a unique methodological contribution through its systematic collection of voluntary self‑identification data, enabling multidimensional analysis of inclusion and exclusion. By complementing register data, the survey also contributes theoretically by facilitating more precise empirical analyses of superdiversity, inclusion, and the changing contours of the social mainstream in contemporary Sweden.