The purpose of this study was to examine the reliability, validity, and classification accuracy of the DSM-IV diagnostic criteria for pathological gambling. Given the lack of a laboratory test to diagnose pathological gambling, two groups were recruited in order to test DSM-IV diagnostic classification accuracy, one which likely had the disorder and the other which likely did not have the disorder (121 men and women clients at a gambling treatment facility) (138 men and women selected at random from the Windsor, Ontario, community who had gambled in the past twelve months). The Gambling Behavior Interview was administered to both groups. The Gambling Behavior Interview includes items that measure the ten DSM-IV diagnostic criteria for pathological gambling as well as other gambling problem severity measures and scales that served as tests of convergent validity. The ten DSM-IV diagnostic criteria were found to exhibit satisfactory reliability, validity, and classification accuracy; however, lowering the cut score to four and using item weights yielded improved classification accuracy over the standard cut score of five. Some diagnostic criteria were found to have greater discriminatory power than other criteria. The results of this study suggest that the classification accuracy of DSM-IV diagnostic criteria can be improved upon with a lower cut score or using weighted criteria.