This appendix describes the data and methodology used to estimate federal program and tax expenditures on children in "Kids' Share 2021: Report on Federal Expenditures on Children through 2020 and Future Projections" (ED616306). The following contents are included in this appendix: (1) Introduction; (2) Summary Table of Multipliers and Expenditures in 2018; (3)Income Security Programs; (4) Nutrition Programs; (5) Housing Programs; (6) Tax Programs; (7) Health Programs; (8) Social Services Programs; (9) Early Care and Education Programs; (10) Education Programs; (11) Training Programs; (12) Works Consulted; and (13) Acknowledgments.