This study measures the change in preventive health care use after enrollment into a new public insurance program for low-income childless adults. Data come from claims from a large integrated health system in rural Wisconsin and Medicaid enrollment files between January 2007 and September 2012. We employ individual level fixed effects poisson models and regression discontinuity to examine preventive care visits for two years before and after insurance enrollment for two samples of previously uninsured low-income adults that differ according to participation in safety net programs. We also determine whether the impacts of public health insurance on the use of preventive care differ for men and women.  Preliminary results show that, among both safety net patients and non-safety net patients, public insurance enrollment led to substantial increases in preventive care visits, though overall outpatient visits fell overall among safety net patients while they increased among non-safety net patients. These preliminary results suggest that public insurance expansions to childless adults have the potential to increase access to and use of preventive services and have the potential to improve health.