In response to the pressing challenges posed by the current societal development trajectory, the idea of sustainability as an alternative, safe, and just development paradigm has received wide traction in different societal sectors. Higher education institutions are recognized as key players in fostering societal change by equipping students with competencies that support them in solving sustainability challenges. One essential ability of a sustainability-competent students is to assess a given problem from multiple sustainability perspectives. This ability requires elaborated conceptions of the abstract idea of sustainability. Currently, higher education institutions, however, seem to fall short in sufficiently equipping students with elaborated sustainability conceptions. Embedded in research on higher education for sustainable development (HESD) and conceptual change, this dissertation empirically investigates how studying at such an institution affects changes in and developments of undergraduates’ sustainability conceptions. An exploratory literature review identified gaps in prior research, underscoring the need for systematically investigating sustainability conceptions. Based on this, sustainability conceptions were defined as individual representations of the abstract idea of sustainability and an assessment instrument to measure changes in sustainability conceptions was developed. Further, this dissertation employs a mixed-methods approach consisting of a multi-cohort longitudinal study combined with narrative interviews that allows for long-term monitoring of changes as well as analyzing students’ subjective perceptions of their learning processes. This dissertation indicates that an undergraduate program with an initial mandatory sustainability-related first semester module in combination with further optional sustainability-related learning offers has shown certain potential in instigating changes of sustainability conceptions within all students of different subjects. The results suggest that undergraduates are gradually less likely to associate the economic and ecological dimensions with the concept of sustainable development over the course of three years. However, the changes were only subtle and often only significant in relation to students’ subject affiliations. Notably, students in environmental science exhibit changes towards elaborated sustainability conceptions. This indicates that continuous engagement with sustainability throughout the entire study program is beneficial for elaborated conceptions. The results also add evidence to the notion that effects of sustainability-related learning offers are highly intertwined with the students’ subjective meaning-making processes. In line with findings from conceptual change research, this dissertation highlights the importance of emotions and values in these processes. Thus, creating relevance of the sustainability-related learning offers for all students already in the first semester seems to be a key factor for preventing loss of interest and in consequence less elaborated sustainability conceptions. While the insights presented in this research are primarily focused on a higher education institution of medium size that has already implemented sustainability in a whole institution approach, it holds significant implications for researchers and practitioners aiming to analyze and enable conceptual change in students from different subjects.