Abstract: The Repository of Psychological Instruments in Serbian (REPOPSI; https://osf.io/5zb8p/), run by the Laboratory for Research of Individual Differences at the University of Belgrade and hosted on the Open Science Framework, is an open-access repository of psychological instruments. REPOPSI is a collection of over 130 instruments (e.g., scales, tests) commonly used in social and behavioral science research. Documented are Serbian, English and multilingual instruments, which can be used free of charge for non-commercial purposes (e.g., academic research or education). We argue that REPOPSI enables scientists to increase the efficiency of their research and the visibility of their output. We analyze REPOPSI’s commitment to ensure that its (meta)data is findable, accessible, interoperable, and reusable (the FAIR Data Principles) and its trustworthiness with respect to transparency, responsibility, user focus, sustainability, and technology (the TRUST principles). Finally, we describe how the FAIR and the TRUST principles will support the process of continuous improvement of REPOPSI.