The diversion of medications by physicians is a seldom discussed problem in the United States. A better understanding of the mechanisms of diversion could assist decision makers as they develop preventive policies. To identify these mechanisms, nine focus groups of physicians undergoing monitoring for substance abuse by a state-based physician health program were conducted. The content analysis revealed that physicians divert medications by stealing from the office or hospital, by defrauding patients and insurers, by using medication samples, and by misusing valid prescriptions. The implementation of policy interventions targeting these mechanisms has the potential to mitigate the amount of physician diversion that occurs.