‘Leave no one behind’ is a core principle of the Sustainable Development Goals (SDGs). While the SDGs do not explicitly refer to ‘social exclusion’, the framework notes the relationship between poverty eradication and inequality within and among countries. In this chapter, we argue that inequality and poverty can only be eradicated if development initiatives recognize and engage with the precarious lives of people who are marginalized because of their sexual orientation, gender identity and expression (SOGIE). This chapter draws on a legacy of research in gender, sexuality and development to identify mechanisms of ‘social exclusion’ that have, to date, negatively shaped the lives of marginalized groups around the world. Social exclusion is considered, first, at a societal level, and we demonstrate how it is reinforced through punitive laws and cisnormative policies. Second, we explore how social exclusion operates at an institutional and infrastructural level, often through the absence of services that can address multidimensional poverty among sexual and gender minorities. These findings are based on a comprehensive review of empirical studies that document links between social exclusion and poverty among sexual and gender minorities. We argue that without careful attention to the societal and institutional dynamics of exclusion, the current SDG framework runs the risk of entrenching rather than addressing inequality and poverty among those very groups who already experience profound marginalization on the basis of their sexuality and gender.