Environmental justice (EJ) scholarship is increasingly framing justice in terms of capabilities. This paper argues that capabilities are fundamentally about well-being and as such there is a need to more explicitly theorize well-being. We explore how capabilities have come to be influential in EJ and how well-being has been approached so far in EJ specifically and human geography more broadly. We then introduce a body of literature from social psychology which has grappled theoretically with questions about well-being, using the insights we gain from it to reflect on some possible trajectories and challenges for EJ as it engages with well-being.