This paper analyzes the quantitative impact of an intervention that provides subsidized low-cost private health insurance together with health facility upgrades in Nigeria. The evaluation, which measures impact on healthcare utilization and spending, is based on a quasi-experimental design and utilizes three population-based household surveys over a 4-year period. After 4 years, the intervention increased healthcare use by 25.2 percentage points in the treatment area overall and by 17.7 percentage points among the insured. Utilization of modern healthcare facilities increased after 4 years by 20.4 percentage points in the treatment area and by 18.4 percentage points among the insured due to the intervention. After 2 years of program implementation, the intervention reduced healthcare spending by 51% compared with baseline, while after 4 years, spending resumed to pre-intervention levels.