In 2017-18, states and districts began to implement the Every Student Succeeds Act (ESSA), the current authorization of the federal Elementary and Secondary Education Act (ESEA). ESSA continues to call for states to set academic content standards, assess student achievement, identify and support low-performing schools, and improve educator effectiveness. ESSA departs from prior law, however, in giving states more discretion about how they accomplish these objectives. This report provides a brief look at the transition toward ESSA, as the foundation for an ongoing assessment of how the law is being carried out. The report uses survey data to examine how key policies and initiatives related to two large ESEA programs were implemented in 2017-18, and contrasts that with four years earlier. Key findings indicate that: (1) Most states had not significantly changed their content standards by 2017-18, and districts increasingly provided supports, such as standards-aligned instructional materials, to implement them; (2) States broadened the measures they used to identify struggling schools, while more districts reported that these schools implemented activities to support improvement, particularly teacher professional development; and (3) States and districts increasingly used performance data as a means to support effective teaching. [For "The Transition to ESSA: State and District Approaches to Implementing Title I and Title II-A in 2017-18. Supplemental Volume. NCEE 2021-002sv," see ED609180. For "The Transition to ESSA: State and District Approaches to Implementing Title I and Title II-A in 2017-18. Study Highlights. NCEE 2021-002," see ED609181.]