Although Spanish-speaking lands are often imagined as lands of sexual intolerance, Buenos Aires is better characterized by ineffectual repression and by its recent celebration of sexual diversity. In this chapter we analyze sexuality in Buenos Aires against the backdrop of economic, socio-demographic, cultural, and political transformations that often undermined the regulations of authorities. The decades between 1880, when Buenos Aires became the capital, and the overthrow of President Juan Perón in 1955 were crucial for the formation of modern Argentina and constitute its focus. We begin with some preceding historical trends in the colonial and early independent era, and end with a succinct analysis of a few salient trends after 1955, especially those leading to Buenos Aires becoming a leader of LGBTQ+ rights in the twenty-first century. We discuss immigration, class differences in sexual behaviours, commercialized sex, sexual diversity with marica and homosexual identities, the rise of family sociability, and the push for sexual ‘normalcy’.