Six of the 32 states implementing the Affordable Care Act’s Medicaid expansion to date have done so through Section 1115 waivers. Using these waivers, the Centers for Medicare and Medicaid Services has approved terms that extend beyond the flexibility provided by federal law. Section 1115 waivers authorize research and demonstration projects that, in the view of the Health and Human Services Secretary, further the purposes of the Medicaid program. The ACA implemented new requirements for these waivers, including that states must have a publicly available, approved evaluation strategy. States also must submit an annual report to HHS that describes the changes occurring under the waiver and their impact on access, quality, and outcomes.