The policy diffusion framework is critical to understanding the spread of policy innovations such as charter schools in the United States. This framework, however, is less instructive in explaining the state-by-state configuration of these policies. What explains the wide variation in charter school policy among states? This study addresses this question by introducing the concept of policy regimes. Policy regimes capture dominant and distinct approaches to policy innovations that are informed by common institutional environments among states. This article applies this concept to charter schools by studying state charter school policies and their effects on academic performance. Factor analysis of different charter school policies identifies four unique policy regimes: independence, support, accountability, and mandate. These four regimes are linked to a series of state characteristics. This article then examines the relationships between regime type and charter school performance using ordinary least squares (OLS) regression models. The results show that regime types are statistically related to charter student achievement in ways that are consistent with each regime's policy approach. These finding suggest that policy regimes may be important in disentangling the apparent variation in charter school performance.