Perceptions acquired during tertiary health promotion education can influence students' interactions with their future service-users. Reflective practice can highlight these perceptions. Here we describe the findings of a reflective exercise conducted with postgraduate health promotion students as part of a learning activity. Students (n = 44) reflected on their understandings of at-risk populations in three priority areas-tobacco, obesity and alcohol. The activity aimed to deconstruct students' understandings of these populations and identify understandings juxtaposed to the philosophical underpinnings of health promotion, for addressing through teaching and learning. Thematic analysis revealed students' understanding of all three at-risk populations fit within five themes: apathy/lack of altruism, complexity/choice, pressure/control, escaping /excuses, and environmental contexts. Students also have varying levels of tolerance to at-risk populations, expressing greatest tolerance towards those whose addiction undermines choice and self-control, and least towards those who are overweight/obese or whose behaviour causes risk to others. Our findings show reflective practice is a valuable tool to help educators understand students' attitudes and values and implement changes to support their future role in the community.