The American Psychiatric Association currently is in the process of updating the Diagnostic and Statistical Manual of Mental Disorders to its fifth edition (DSM-V). The DSM is the handbook of mental disorders in the United States, used daily by health care providers, researchers, insurance companies and government agencies. The DSM-V Work Group that reviewed the diagnosis for pathological gambling has proposed several changes to the diagnostic definition of the disorder. Revisions in diagnostic codes are typically driven by evolving research that transforms our understanding of a disorder, and so this month’s Issues & Insights summarizes several studies that question the current definition of pathological gambling and, in some cases, might inform the final recommendations for the DSM-V.