[영문]Between 1920 and 1940, fertility dropped below replacement level in many Western countries. In today's scholarly literature, the drop is usually explained as a temporary reaction to the exceptional conditions of the inter-war period. This paper confronts that interpretation with the interpretations offered by scholars writing between the wars. According to leading demographers of the time, low fertility was due not to war or economic crisis, but rather to processes that now tend to be associated with the Second Demographic Transition, including secularization, individualization, rising consumerism, and women's emancipation. Since these were seen as structural features of modernization, most inter-war scholars argued that subreplacement fertility would remain an obstinate feature of modern society for an extended period of time.