This doctoral thesis examines transnational flows of scientific and social knowledge which shaped the understanding and experience of sexually dissident masculinities in Britain in a period of west European reconstruction and Cold War politics. Focussing on male homosexuality, the research traces how European sexual knowledge was translated into a British context, with its distinct national legislative and discursive framework between the end of the Second World and the emergence of a more radical gay rights movement in the 1970s. Placing homosexuality within networks of European sexological research, international political activism and subcultural activity, the thesis establishes how these influences reshaped official approaches and the self-conception of homosexual men in Britain. My thesis expands scholarship which has addressed male homosexuality and the regulation of dissident masculinities within distinct national frameworks. This is achieved with a transnational methodology which foregrounds the significance of cross-border exchanges in shaping national and local sexual norms and identities. Over four chapters, the thesis examines interconnections between British and continental European histories of homosexuality, highlighting that processes of knowledge diffusion and cultural adaptation were complex and constrained by distinct cultural and political traditions. Chapter One analyses the transnational origins of the Wolfenden Report, a key document which shaped 1967 law reform. Chapter Two investigates how the political and social aspirations of British homophile and gay rights groups in the 1950s and 1960s were shaped by wider transnational movements for homosexual equality, while Chapter Three traces how an international political language of sexual equality was translated into the British context. The final chapter charts the more informal encounters and networks of cultural communication forged by homosexual men themselves during the post-war tourist boom. My use of extensive and underutilised archival sources includes the papers of the Wolfenden Committee at the British National Archives, documents relating to international homophile organisations at the National Archives of the Netherlands, a large collection of contemporary domestic and international homosexual journals which were accessed at the LSE Hall-Carpenter Archives and a number of international LGBT archives, as well as Oral Histories at the British Library Sound Archive. These sources are used to map contemporary homosexual experience and to challenge narratives of British post-war sexual rights movements as isolated and separate.