Abstract Executive federalism emphasizes collaboration between the executive branches at the national and state levels to transform grant programs through the implementation process. In this regard, Medicaid demonstration waivers loomed large during the presidencies of Bill Clinton and George W. Bush. This article docu-ments and compares the volume and substance of section 1115 Medicaid waiver activ-ity under the two presidencies. From the perspective of policy performance, Medicaid demonstration waivers provide modest support for the view that states serve as labora-tories for policy learning in the health care arena. More broadly, the waivers have not yielded a major solution to the problem of the uninsured and are unlikely to do so. At t...