Learning outcomes in higher education for sustainable development (HESD) have become a major focus in recent years. One of the key learning outcomes are students’ sustainability conceptions which enable individuals to assess a problem from multiple sustainability perspectives in order to deal with complex sustainability issues in their future professional fields. Universities, however, seem to fall short in sufficiently equipping students with more elaborated sustainability conceptions. One reason is probably that none of the existing frameworks links sustainability conceptions to the influencing factors on all levels of higher education over the course of the studies. If universities want to monitor learning processes in their students’ sustainability conceptions, they should consider all internal and external conditions influencing the learning process in the higher education system. Thus, further research efforts need to be pursued regarding the operationalization of learning outcomes. Therefore, this qualitative research synthesis study proposes a process-oriented framework of internal and external factors that influence students’ sustainability conceptions. Hence, this paper contributes to the literature in HESD by moving away from a focus on individual students or cross-sectional course evaluations towards an understanding of what shapes students’ sustainability conceptions over time. Although exploratory, the framework is intended to be used as a general scheme of how to operationalize learning processes for the design of curricula, courses or monitoring in HESD.