Significant controversy surrounds the use of hydraulic fracturing (fracking) in oil and gas extraction in the United States.To address some of these concerns, states are leading the charge by regulating the process. Yet, variations exist in state regulatory approaches, and it is still unclear what drives these differences. Thus, this research applies policy subsystem theory to examine original interview data to determine what may cause these variations in regulations through an examination of Colorado, Wyoming, and Louisiana. This research finds that policy subsystem theory is useful in explaining this variation.In particular, the position of agency staff and privileged stakeholder groups, often industry related, help to explain why Colorado has a much stronger regulatory program than Louisiana. In comparison, Wyoming's stringent regulations represent the anomaly in this case, but the results of this research suggest that this dominant energy subsystem will likely not be setting any pro-environment trends going forward.