Although integration is often considered critical to success or failure of inter-and trans-disciplinary (ITD) research projects or programs (Defila et al., 2006; O'Rourke et al., 2016), widespread consensus on what integration actually means is lacking (O'Rourke et al., 2019; Pohl et al., 2021). We treat integration as a process of combining a wide range of perspectives not only from different disciplines (interdisciplinary integration), but also from research, policy, and practice (transdisciplinary integration) in order to advance fundamental understanding of complex societal problems, and to formulate 'socially robust' solutions (Hoffmann et al., 2017a). We likewise refer to integration as the result or output that emerges from this process (O'Rourke et al., 2016). Following O'Rourke et al. (2019) and Pohl et al. (2021), integration occurs at different phases of an ideal-typical ITD research process and yields different types of integration in different contexts depending among others on the specific purpose, scale and scope of ITD projects or programs (Klein, 2008). Finally, we distinguish knowledge elaboration from knowledge regulation (Lund, 2019). We argue that integration does not happen automatically, but needs to be proactively led to ensure research projects or programs live up their ITD ambition (Hoffmann et al., 2017b; Deutsch et al., 2021). We also posit that leading integration does not take place in a vacuum (Brundiers et al., 2013), but requires conditions enabling integration. This contribution explores what kind of enabling conditions project or program leaders and researchers need-and create-to leverage integration. It draws lessons from a variety of cases across various geographical regions, specifically