While recent survey findings suggest graduate programs in health service psychology (HSP) are allocating the same or increased time to education and training in psychological assessment over the last two decades, there is a lack of clear guidance for programs to implement practices associated with quality education and training. These Guidelines (found in full at https://www.apa.org/about/policy/guidelines-assessment-health-service.pdf) were developed to address this critical need. Developed by a task force of the American Psychological Association Board of Educational Affairs in 2018 and 2019, the Guidelines serve to inform faculty/supervisors, students, and the public as to quality practices associated with graduate education and training in psychological assessment. They are organized around seven domains: theory; psychological assessment process; psychometrics; tests and methods; ethics, legal issues, and professionalism; diversity; and supervision. These domains are drawn from a review of the scholarly literature on psychological assessment, as well as graduate psychology education and training. The domains and their associated Guidelines are interdependent, and, while some overlap exists among them, they should be considered in their entirety. While a summary of each section is provided in the present article, the full explanation of each domain is presented in the actual Guidelines document. (PsycInfo Database Record (c) 2021 APA, all rights reserved).