This study evaluated the efficacy of a cognitive treatment package for pathological gambling. Sixty-six gamblers, meeting DSM-IV criteria for pathological gambling, were randomly assigned to treatment or wait-list control conditions. Cognitive correction techniques were used first to target gamblers' erroneous perceptions about randomness and then to address issues of relapse prevention. The dependent measures used were the South Oaks Gambling Screen, the number of DSM-IV criteria for pathological gambling met by participants, as well as gamblers' perception of control, frequency of gambling, perceived self-efficacy, and desire to gamble. Posttest results indicated highly significant changes in the treatment group on all outcome measures, and analysis of data from 6- and 12-month follow-ups revealed maintenance of therapeutic gains. Recommendations for clinical interventions are discussed, focusing on the cognitive correction of erroneous perceptions toward the notion of randomness.