Purpose: The purpose of this paper is to examine the impacts of a sustainability course that was designed to evoke measurable transformational changes in students' preferences and in their roles as consumers, employees and citizens, via consciously addressing sustainability issues and involving a community partner. Design/methodology/approach: The research was undertaken using mixed methods. Q-methodology helped create student groups with similar preferences for sustainable attitudes and behaviours before and after the course; the most important features of attitude changes and identify the phases of transformation were explored. In-depth interviews with each participant contributed to understanding and explaining the motivation for changing preferences and generated individual-level reflections about the perceived process of transformation. Findings: Q-method highlighted how stakeholder roles were transformed from the three pre-factors to the three post-factors and for the whole group. Seven phases of transformational change are identified based on the reflective in-depth interviews from "no transformation" to "change agent behavior". Practical implications: Findings provide new perspectives for evaluating and embracing the transformational potential of sustainability courses. Originality/value Assessing the impacts of sustainability courses on students' transformation via measuring their mindsets and behaviour preferences prior to and after a course is still an under-researched area, especially in relation to the Q-method. A further unique feature is how the influence of engaged community partner on students' preferences is captured. The explored scope of individual responsibility goes beyond environmental awareness and addresses participants in various stakeholder roles simultaneously, by examining their priorities as consumers, employees and citizens.