Medicaid expenditures account for a sizeable proportion of U.S. GDP - 360.3billionin2009or2.55percentofGDP.Despitethis,theAffordableCareActof2010(i.e.thenewObamahealthcareinitiative)furtherexpandseligibilitycriteriafortheMedicaidprogram.However,thereislittleliteratureontheeffectonhealthcarespendingfromearlierexpansionsofMedicaidsuchastheintroductionoftheSCHIPprogram.Moreover,theeffectofwelfarereform(i.e.PersonalResponsibilityandWorkOpportunityReconciliationActof1996)onMedicaidspendinghasreceivedlittleattention.Usingpaneldatafromall50U.S.statesfortheperiod1990−2004,wefindthataddingonepersontotheSCHIProllsinastatethathasestablishedanSCHIPprograminMedicaidraisesrealMedicaidspendingabout4,100. However, we find evidence that additional SCHIP enrollments also affect non-Medicaid health spending. Thus, the total costs of insuring these patients are significantly higher (about 7,700).ForstatesthathaveestablishedMedicaid−combinedprograms,addingonepersontotheSCHIProllsraisesrealhealthcarespendingabout1,800 after two years. Finally, we find that welfare reform reduced annual Medicaid expenditures by about 1.2billionandtotalhealthcarespendingbyabout2.5 billion