In January 2017, the Chairmen of the Senate Finance Committee, the House Energy and Commerce Committee, the Energy and Commerce Health Subcommittee, and the Energy and Commerce Oversight Subcommittee requested a study on optional eligibility groups and optional benefits covered in each state. This presentation previews a draft of that study, to be published as Chapter 3 of the June 2017 Report to Congress on Medicaid and CHIP. Findings describe national and state-level enrollment and spending on mandatory and optional populations and services.