This research study explores the policy expansion of school choice within the methodological approach of event history analysis. The first section provides a comparative overview of state adoption of public school choice laws. After creating a statistical portrait of the contemporary landscape for school choice, the authors introduce event history analysis as a methodological solution to the problem of measuring policy expansion. Building on previous studies in the social science literature, we proceed to discuss political, economic, and social factors related to the passage of charter school laws. A multivariate analysis finds state adoption is significantly related to partisan gubernatorial control, classroom spending, private schools, education finance litigation, and minority representation. The final section discusses the empirical results in the modern policy environment and proposes future directions for comparative state research.