From 1894 to 1971, "same-sex fornication" was a crime in Finland. However, a wide variation can be seen in the degree to which same-sex relations were controlled during the existence of the law. From the 1930s onwards, the number of convictions started to rise, reaching its peak in the early 1950s and dropping sharply in the latter half of the 1960s. This research studied the ways in which male same-sex desire was perceived, controlled and lived through during the first seventy years of twentieth-century Finland. The longitudinal-type analysis provided the perspective to view the transformations in discourses on male sexual practices and their impact on actual policing. The research question was elaborated through the microhistorical narratives of seven men who had been convicted of same-sex fornication in different decades of the twentieth century. The theoretical basis of the dissertation was queer theory. The main sources were same-sex fornication court case documents which were read together with legal, medical and moral writings, and newspaper and tabloid articles. By combining micro- and macro-dimensions, the research was able to reveal the changing attitudes towards male sexual intimacy in Finnish society, and by comparison to European historiography the study showed the roots of these attitudes. Until the late 1920s, the Hirschfeldian view on male sexual intimacy was dominant in Finland as well as in other Nordic countries. However, the dissertation shows how in the 1930s Finnish medical and legal authorities adapted the Nazi German perception of homosexuality as a transmittable disease, which increased control over male-male sexual practices in Finland at the same time that they became decriminalized in other Nordic countries. In Finnish agrarian society, male sexual practices were tolerated and not labeled, and boys were not viewed as possible victims of sexual abuse. Men who exclusively and extensively sought sex with other men or boys were called manlovers until the Second World War and the immediate post-war period, when sexual presentations of Finnish men were nationalized, and homosexual practices were constructed as unmanly and dangerous. Homosexual emancipation took place fast alongside the "sexual revolution" in the latter part of the 1960s.