Establishing a Transactive Memory System (TMS) is essential for groups of learners, when they are multidisciplinary and collaborate online. Environments for Computer-Supported Collaborative Learning (CSCL) could be designed to facilitate the TMS. This study investigates how various aspects of a TMS (i.e., specialization, coordination, and trust) can be facilitated using a transactive memory script that spans three interdependent processes (i.e., encoding, storage, and retrieval) in multidisciplinary CSCL. Sixty university students were assigned to multidisciplinary pairs based on their disciplines (water management or international development). These pairs were randomly assigned to a scripted or non-scripted condition and asked to discuss and solve a problem case. The script facilitated construction of a TMS, fostered learners' knowledge transfer and convergence, and improved the quality of problem solution plans. Specialization and coordination aspects of the TMS were mediators for the impacts of the script on joint but not individual problem solution plans.