Though the Sustainable Development Goals (SDGs) were crafted through an inclusive process, research on the relationship between greater female or younger legislative representation and SDG performance has been lacking. This article employs a linear mixed effects modeling approach to shed light on this relationship. Controlling for economic and democracy levels and population, the modeling reveals a positive correlation between female and youth legislative representation and SDG performance. Additional analyses, however, suggest the strength of the relationships with female and youth legislative representation vary between the socioeconomic and environmental SDGs. Female and youth representation are strongly correlated with the socioeconomic SDG index; they improve the fit of the model for the environmental SDG index. This result may stem from a tendency in developed countries to trade off the environmental SDGs for the socioeconomic SDGs. It may also imply that greater legislative representation is not sufficient to overcome constraints in energy and consumption and production systems that often lead to those trade-offs. Rather bringing women and younger people into legislatures may need to be combined with institutional and policy reforms that turn socioeconomic and environmental trade-offs into synergies.