In this chapter, the basic concepts of housing and welfare are clarified by editors Martin Grander and Mark Stephens. The notions of welfare regimes and housing regimes are defined and elaborated, discussing the distributional logic of welfare and housing in different contexts. The chapter discusses the basis for Esping-Andersen’s classic typology of welfare regimes as well as more recent developments, critiques, and alternative understandings of such a categorization. Regarding housing, the authors first introduce how comparative approaches to theorize housing have mirrored approaches more closely focused on welfare states. Here, the “housing-welfare regime” framework, founded by Kemeny, serves as the main point of departure. Thus, the chapter introduces and summarizes the two principal articulations of regime theory as applied to the welfare state and to housing, as well as the key studies that preceded them. It also highlights the political and economic context in which these regimes were created in the 20th century and how this has changed under the pressures of economic globalization and political fragmentation. The chapter also demonstrates how regime theory has bifurcated between housing and the wider welfare state and this inevitably inhibits our ability to understand the relationship between them, particularly in a changing world.