PROJECT SUMMARY This application is for an administrative supplement to DA058314, Development of practical screening tools to support targeted prevention of early, high-risk drinking substance use. The purpose of the supplement is to preserve, generalize, document, and disseminate a unique research material we have developed for the DA058314 project. Namely, we aim to create an open-source toolkit of bespoke metadata, code, and workflows that will allow end-users to quickly create and evaluate practical instruments for screening or prediction of any outcome of their choosing in the ABCD Study. Today, the breadth and complexity of the ABCD Study poses a major barrier to outside users pursuing the development of screeners or other prediction instruments. By lowering these barriers, the toolkit we develop will unlock the unprecedented potential of the ABCD Study for developing accurate, equitable approaches to risk estimation and prediction, in turn improving the ability of clinicians, policymakers, and scientists to allocate resources efficiently. We will disseminate the toolkit via a free R package, a website, peer-reviewed publications, and webinars. The administrative supplement is needed to support an additional staff member whose time will be devoted to these activities and complete this work in parallel to ongoing work on the parent award.