Since research data services were first offered within our institutional repository, community interest and dataset deposit counts have both grown steadily. While primarily focused on housing traditional scholarship and publications, the institutional repository also provides a discipline-agnostic storage and access solution for datasets for the university. Given a landscape in which publishers and funding agencies are putting increasing emphasis on open sharing of research data, it is critical that researchers feel confident entrusting their data to our repository. In 2019, library staff began the process of seeking CoreTrustSeal certification of our institutional repository as a trustworthy data repository. As we composed our application and then iterated through cycles of feedback, editing, and resubmission, the extensive self-assessment led to several valuable observations. We identified areas of improvement necessary to meet the certification requirements, as well as shortcomings in our public-facing policies and documentation. We were also able to recognize the extent to which our institutional knowledge about the repository had been siloed. As a result, we took action to share knowledge within the organization, update our public-facing policies, and strengthen governance. The process also led us to update and formalize digital preservation strategies across the library. In this presentation, the authors will describe our motivations for seeking CoreTrustSeal certification and our experience of the application process. We will examine the outcomes of our self-assessment for our repository staff and for our users. Finally, we will address the significance of trustworthy data repositories for the community of researchers that we support, especially considering recent developments like the NIH data management and sharing policy.