The Elementary and Secondary Education Act (ESEA) was comprehensively reauthorized by the Every Student Succeeds Act (ESSA; P.L. 114-95) on December 10, 2015. The Title I-A program is the largest grant program authorized under the ESEA and is funded at $15.8 billion for FY2018. Title I-A of the ESEA authorizes aid to Local education agency's (LEAs) for the education of disadvantaged children. Title I-A grants provide supplementary educational and related services to low-achieving and other students attending pre-kindergarten through grade 12 schools with relatively high concentrations of students from low-income families. Title I-A has also become a vehicle to which a number of requirements affecting broad aspects of public K-12 education for all students have been attached as conditions for receiving Title I-A grants. Under Title I-A, funds are distributed to state educational agencies (SEAs) and (LEAs) based on four formulas. The ESSA made few changes to these formulas. One notable change is an increase in the set-aside for the Bureau of Indian Education (BIE) and Outlying Areas from 1.0% to 1.1%. This change will take effect beginning in FY2017 provided the total amount available for state grants would not be less than the amount available in FY2016. All changes to the Title I-A grant allocation process made by the ESSA will take effect beginning in FY2017. This report provides a detailed discussion of the four Title I-A formulas used to determine grants as modified by the ESSA. Table A-1 in Appendix A offers an overview of the key elements included in the four formulas. Appendix B provides an overview of Title I-A appropriations levels in recent years. [Elizabeth Crowe, former Research Assistant at CRS, also contributed to this report.]