<h3>Background</h3> Nutrition and dietetic (N&D) professionals can contribute to sustainable development and achievement of the United Nations' Sustainable Development Goals. However, there are diverse understandings of what sustainability means in the N&D context which may be constraining higher education curricula. <h3>Objective</h3> To explore the concept of ‘sustainability' in the context of N&D from student, academic, and practitioner perspectives. <h3>Study Design, Setting, Participants</h3> An action research process was used to explore the concept of sustainability. Data was collected sequentially, first from undergraduate students' self-reported perceptions of sustainability (n = 95, self-administered online survey, open question) and then academics' perceptions of sustainability-related teaching practice (n = 7, workshop) at a regional Australian university. Semi-structured interviews were then undertaken with Australian N&D practitioners (n = 10) having longevity in the dietetic/nutrition profession as well as a specialist practice area. Data was analysed concomitantly and used as a sensitising device with each subsequent group. <h3>Measurable Outcome/Analysis</h3> Students provided 4 keywords/phrases conveying their personal understanding of sustainability within the N&D context. Academics provided a written response to the question; how do you perceive sustainability? Practitioners answered questions from an interview protocol developed to enable exploration of sustainability both conceptually and in practice. Each data set was analysed for theme by 2 independent researchers. Findings across participant groups were then analysed for overarching themes. <h3>Results</h3> Across groups, sustainability was perceived as a broad, future-focused concept, multi-factorial (environment, culture, social, economic), and relating to dietary recommendations and practices. Themes from student responses were sustainable food systems and system influencers. Academic and practitioner themes diverged to include sustaining the profession, sustaining the effects of our work, and stewardship of resources. Sustainability was characterised as conflicted, action-oriented, context-dependent, and inter-disciplinary. <h3>Conclusions</h3> Student, academic, and practitioner perceptions may be useful in forming a working definition to clarify sustainability in the N&D context for curriculum development.