When the primary federal law governing K-12 schooling was updated in 2015 as the Every Student Succeeds Act (ESSA), it shifted many decisions to states and districts. However, through two of its core programs (Title I and Title II-A), ESSA retained federal requirements for states to set challenging content standards, assess student performance, identify and support low-performing schools, and promote the development of the educator workforce. Title I encourages equal access to education by funding districts and schools serving a high percentage of students from low-income families. Title II-A aims to improve the effectiveness of teachers and principals. How states and districts respond to the combination of flexibility and requirements will determine whether ESSA stimulates educational improvement as intended. This report is part of a study describing the implementation of Title I and Title II-A at key timepoints, through surveys of all states and a nationally representative sample of districts. The report compares the actions of states and districts from the 2013-14 school year (prior to ESSA) to the 2017-18 school year (during the transition to ESSA). A future report will examine implementation in the 2021-22 school year, after districts have had more time to implement any state policy changes. [For "The Transition to ESSA: State and District Approaches to Implementing Title I and Title II-A in 2017-18. Evaluation Report. NCEE 2021-002," see ED609179. 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.]