Retail clinics have the potential to reduce health spending by offering convenient, low-cost access to basic health care services. Retail clinics are often staffed by nurse practitioners (NPs), whose services are regulated by state scope-of-practice regulations. By limiting NPs' work scope, restrictive regulations could affect possible cost savings. Using multistate insurance claims data from 2004-07, a period in which many retail clinics opened, we analyzed whether the cost per episode associated with the use of retail clinics was lower in states where NPs are allowed to practice independently and to prescribe independently. We also examined whether retail clinic use and scope of practice were associated with emergency department visits and hospitalizations. We found that visits to retail clinics were associated with lower costs per episode, compared to episodes of care that did not begin with a retail clinic visit, and the costs were even lower when NPs practiced independently. Eliminating restrictions on NPs' scope of practice could have a large impact on the cost savings that can be achieved by retail clinics.