Understanding equitable practice is crucial for science education since science, technology, engineering, and mathematics (STEM) fields and STEM learning practices remain significantly marked by structural inequalities. In this paper, building on theories of discourse and situated meaning developed by Foucault, Gee, and Sedgewick, we explore how educators navigated discourses about social justice in informal science learning (ISL) across four UK sites. We draw on qualitative, multimodal data across 5 years of a research--practice partnership between a university, a zoo, a social enterprise working to support girls and nonbinary youth in STEM, a community digital arts center, and a science center. We identify three key discourses that shaped social justice practices across all four practice--partner sites: (1) "inclusion" for STEM, (2) "inclusion" for the institution, and (3) "inclusion" for minoritized youth. We discuss how educators (n = 17) enacted, negotiated, resisted, and reworked these discourses to create equitable practice. We argue that while the three key discourses shaped the possible meanings and practices of equitable ISL in different ways, educators used their agency and creativity to develop more expansive visions of social justice. We discuss how the affordances, pitfalls, and contradictions that emerged within and between the three discourses were strategically navigated and disrupted by educators to support the minoritized youth they worked with, as well as to protect and promote equity in ISL. This paper contributes to research on social justice in ISL by grounding sometimes abstract questions about power and discourse in ISL educators' everyday work.