Objective Evaluate how the use of a Section 1115 waiver in Arkansas was associated with health insurance coverage compared to Medicaid expansion states that did not use a waiver. Methods Difference in difference analysis was conducted of 1,320,790 adults aged 19-64 with family incomes at or below 138% of the federal poverty level from the 2010-2017 American Community Survey. Arkansas was compared to states that expanded without a waiver in calendar year 2014. States that expanded Medicaid with an approved Section 1115 waiver during the study period or expanded without a waiver after 2014 or did not expand Medicaid were excluded from the analysis. The outcome measures were no health insurance coverage, Medicaid coverage, employer sponsored private insurance, and non-group direct purchase private insurance. Results Arkansas's use of a waiver to expand Medicaid was associated with a lower uninsured rate (-3.7%, p< 0.001), a higher Medicaid coverage rate (2.0%, p< 0.001), and a higher nongroup, direct purchase private insurance coverage rate (2.9%, p< 0.001) compared to states that expanded Medicaid in 2014 without a waiver. Conclusion Compared to states that implemented traditional Medicaid expansion, we found that Arkansas's waiver was associated with increases in health insurance coverage rates.