This chapter discusses “mass tourism” in Western Europe, the most important hotspot of world tourism in the “short” twentieth century (1918-1989). Chronologically structured in three sections, it aims to untangle tourism’s tricky relationship with regional development and nature conservation. First, the rise of a Taylorist tourism model accompanied the emergence of different forms of “social tourism” in the interwar period (e.g., the socialist Naturfreunde movement and fascist tourist organization such as Kraft durch Freude). Second, the rapid rebuilding of the tourism industry and its infrastructure from the 1940s to the 1960s, joined by the establishment of a network of conservation areas, played a vital role in promoting “landscape tourism”. Third, the 1970s and 1980s, which can be characterized by a final stage of mass tourism but also growing ecological awareness, calling for more sustainable forms of “eco-tourism”. This analysis reveals that, while (mass) tourism could be called a pan-European phenomenon, its characteristics were shaped on different levels and by a diverse set of actors with distinct, but very unequal agency.