Purpose: This paper aims to explore the concept of sustainability imaginaries--unifying core assumptions on what sustainability entails held by stakeholders--set within a large suburban Canadian university. The study aims to expand the field of research into imaginaries by focusing on imaginaries within an institution as opposed to a societal or national level. Design/methodology/approach: The paper is conceptual in nature and draws upon empirical tools, such as collaborative thematic coding of interviews of university community members, to illustrate emergent imaginaries around sustainability at the institution. Findings: This paper identifies four core sustainability imaginaries in an analysis of the interview data: sustainability as performance, sustainability as governance, sustainability as techno-efficiency and sustainability as community organizing. The paper then uses these imaginaries to analyse two recent university-wide events: the establishment of a high-level sustainability council and an energy management program. Research limitations/implications: Because of the institutional focus of this study, the research may lack generalizability to other institutions. Thus, researchers are encouraged to explore what other imaginaries may exist at other institutions. Practical implications: This paper includes implications for how universities can manage conflicting expectations and definitions in relation to new sustainability initiatives on campus. Originality/value: This paper offers reflections on the concept of sustainability imaginaries and what they might offer the field of sustainability in higher education.