The exhibition Homosexuality_ies, on view concurrently at the Schwules Museum and the Deutsches Historisches Museum, and the present companion volume offer an overview of the society's handling of homosexuality in light of social, juridical, and scientific repression. At the same time, the show and publication document enduring struggles for equal rights, with an emphasis on developments after the liberalization of 175 in West Germany in 1969. The exhibition understands today's concept of homosexuality as an invention of modernity. Accordingly, it shows historical developments since the late 19th century and concludes with a comprehensive look at the present. That is because today, the common prerequisite for both heterosexuality and homosexuality, namely the assumption of just two sexes/genders, is up for debate. That assumption is being called into question in cultural studies as well as in political discussions, in favor of a diversity of gender identities. While the historical perspective on homosexuality is the focal point at the Deutsches Historisches Museum, contemporary works of art thematize current approaches to sexuality and gender at the Schwules Museum*. The present volume acts simultaneously as a summary and an exciting companion and completion to the exhibition.