Medicaid was created in 1965 with the goal of providing medical coverage to low-income families. After inception the program was gradually expanded to new groups and is now a cornerstone of the U.S. health system. This panel of 4 papers not only offers new insights into previously un-examined impacts of the Medicaid program, but it brings together analysis of 4 phases of Medicaid’s evolution. A large body of research has considered the impact of Medicaid on health insurance coverage, health care utilization, short and medium run health, and financial security. This panel adds to that literature by examining important, but poorly understood features of Medicaid’s impact. The first paper considers Medicaid as an investment in child health and examines the long-term health impact of Medicaid’s gradual introduction across the states in the late 1960’s. The results suggest that exposure to Medicaid in early childhood decreases the prevalence of chronic health conditions in adulthood. Similarly, the second paper considers Medicaid as an investment in human capital and examines the effect of expansions to pregnant women and children in the 1980’s on educational attainment and high school graduation rates. The third paper, set in the late-1990’s when the program was expanded to low-income parents, examines the relationship between Medicaid and employment spells by considering a previously unexamined feature of Medicaid’s impact on health insurance coverage. While most studies have focused on the impact of Medicaid on structural uninsurance, this paper considers the impact of Medicaid on frictional uninsurance. That is, does Medicaid act as a bridge for workers that are transitioning between jobs? Preliminary evidence suggests few workers transitioning between spells of employment take up Medicaid coverage. The final paper, using data from the mid-aughts examines the impact of Medicaid expansions on health insurance coverage and access to care for low-income childless adults. The paper uses the experience of Massachusetts’s 2006 health reform as a case study for guiding expectations about expansions under the Affordable Care Act. The authors find that Massachusetts’s reform effort lead to large increases in health insurance coverage and access to care for low-income childless adults.