During the collective meetings organized in the COST Action, the definition of Middle Class Mass Housing (hereinafter MCMH) came up again and again. This topic, although it was postponing other discussions, revealed a range of interesting cultural variations. We distinguished several approaches to the “middle class” , as well as different ways to define the housing of this multi-faceted social group1. Likewise, the topic of “mass housing” elicited various interpretations. Gradually, we came to the conclusion that it is almost impossible to establish a single definition of MCMH in a continent as diverse as Europe, with its manifold histories, nationalities, cultures, languages, customs and urban planning. This publication aims to illustrate these different perspectives, highlighting the rich variety of housing cultures in European countries and regions.