This article explores the Anglo-transatlantic dimensions of the early twentieth-century sex reform movement through the lens of an emotional economy, which, Hustak argues, marked a specific historical moment in defining political alliances at the level of embodied felt relations of power. The article examines the importance of the collaboration between British and American sex reformers by focusing on how their radical feminist and socialist politics were underpinned by their attacks on jealousy. Hustak suggests here that new transatlantic relationships were forged by British and American sex reformers through their consideration of the emotional constitution of white middle-class citizens who were similarly shaped by capitalist and patriarchal institutions that crossed national divides, while also articulating a special kinship among white middle-class citizens in cosmopolitan bohemian communities on both sides of the Atlantic. Hustak’s use of the term "emotional economy" highlights how white middle-class British and American sex reformers shared similar concerns over a declining white middle-class birthrate, the nervous exhaustion of white middle-class bodies, and the eugenic future of white middle-class civilization. She suggests that sex reformers' campaigns against jealousy highlighted communal ties that defied national boundaries by identifying shared emotional constitutions along the lines of whiteness, eugenic reproduction, and professional work regimes. Hustak uses the specific case study of sex reformer and anarchist Emma Goldman's activities in Greenwich Village as an example of an influential early twentieth-century transnational reformer whose attacks on jealousy as the "'green-eyed' monster" occurred in the wider context of an Anglo-transatlantic politics of emotion.