The Every Student Succeeds Act (ESSA) aims to ensure that all students are college- and career-ready by requiring all schools to implement high-quality accountability systems and services for students. The ESSA impacts assessment practices in schools by requiring staff to account for a broader range of variables related to student well-being, including both academic and non-academic variables (e.g., student mental health). Schools likely will (and should) rely on the expertise of school psychologists in designing and implementing high-quality assessment systems. Thus, school psychologists must be prepared to review a variety of assessment materials and select instruments that are best suited for specific purposes, contexts, and populations. The aim of this article is to familiarize school psychologists with the ESSA requirements for school accountability as well as critical issues in evaluating assessment systems. More specifically, this article presents considerations for evaluating the validity and reliability of assessment tools and procedures. Implications for school psychologists engaged in implementation of the ESSA are described.