<p>The higher education didactic concept of research-based learning is a&#xa0;central element of university teacher training in Germany and integrated into the practical semester in most federal states. The associated expectations regarding the professionalization process of teachers focus on conveying a&#xa0;research-oriented attitude aimed at a&#xa0;professional practice that is not detached from science. We define this attitude as a&#xa0;professional belief, consisting of cognitive, affective, and action-related components, and examine their interaction and longitudinal development.</p><p>Through semi-structured interviews with 22 prospective teachers during their teacher training and early career stages, who engaged with research-based learning in the practical semester, we assess their understanding (cognitive component) and the significance (affective and action-related components) of the concept during these phases. The data are evaluated through content analysis and typology formation to explore phase-specific understanding and significance, longitudinal developments, and their interrelations.</p><p>The findings indicate that understandings of research-based learning vary both during teacher training and early career stages. The concept—according to the respondents’ accounts—is significant for their learning and teaching practice, although not for all and to varying extents. The typology formation illustrates that a&#xa0;lack of significance attributed to research-based learning is associated with misconceptions, while a&#xa0;greater significance becomes apparent when adaptations regarding the concept are made. In terms of viewing it as a&#xa0;professional belief, the initiation of a&#xa0;research-oriented attitude is evident among some respondents.</p><p>Implications for future higher education include the need to support students in adaptation efforts related to their (respective) practice.</p>