Past research indicates associations between higher conservatism and higher life satisfaction, lower neuroticism and higher life satisfaction, and higher conservatism and lower neuroticism. Qualified deduction led to the following hypothesis: Neuroticism can account for the association between higher conservatism and higher life satisfaction. The 50 American states served as the units of analysis. Responses of 619,397 residents to the 44-item Big Five Inventory in an internet survey conducted from 1999 to 2005 provided mean neuroticism scores for each state. Conservative-liberal leaning of over 84,000 respondents to CBS News/New York Times polls from 1999 to 2003 and the percent voting Republican in each state in the 2000 to 2008 presidential elections combined to form a conservatism score for each state. The Gallup-Healthways Well-Being Index provided life satisfaction scores for over 1,000,000 respondents, transforming to a 2008 to 2010 composite score for each state. In a sequential multiple regression equation with life satisfaction as the criterion, state socioeconomic status and white population percent entered first as a block, conservatism entered second, and neuroticism entered third, the demographic controls accounted for 45.7% of the variance, conservatism accounted for another 10.4%, and neuroticism accounted for an additional 10.6%. However, with the entry order of conservatism and neuroticism reversed, neuroticism accounted for another 19.6% but conservatism accounted for only an additional nonsignificant 1.4%. Therefore, the hypothesis was supported. Three alternative explanations suggested by other researchers were not supported in the state-level analysis.