This study examines the prevalence and correlates of DSM-IV pathological gambling (PG) using data from the National Comorbidity Survey Replication (NCS-R), a nationally representative US household survey. The results show that 78.4% of respondents reported lifetime gambling, with 2.3% experiencing problem gambling and 0.6% meeting criteria for PG. PG is significantly associated with being young, male, and Non-Hispanic Black. People with PG first gamble significantly earlier than non-problem gamblers (mean age: 16.7 vs. 23.9). PG typically begins in the mid-20s and persists for an average of 9.4 years, with the largest annual gambling losses averaging $4800. The onset and persistence of PG are predicted by various prior DSM-IV anxiety, mood, impulse-control, and substance use disorders. PG also predicts the subsequent onset of generalized anxiety disorder, post-traumatic stress disorder, and substance dependence. Despite the high prevalence of PG, none of the NCS-R respondents with PG received treatment for gambling problems, but 49.0% were treated for other mental disorders. The study concludes that DSM-IV PG is a rare, impairing, and under-treated disorder, often co-occurring with other mental or substance disorders.This study examines the prevalence and correlates of DSM-IV pathological gambling (PG) using data from the National Comorbidity Survey Replication (NCS-R), a nationally representative US household survey. The results show that 78.4% of respondents reported lifetime gambling, with 2.3% experiencing problem gambling and 0.6% meeting criteria for PG. PG is significantly associated with being young, male, and Non-Hispanic Black. People with PG first gamble significantly earlier than non-problem gamblers (mean age: 16.7 vs. 23.9). PG typically begins in the mid-20s and persists for an average of 9.4 years, with the largest annual gambling losses averaging $4800. The onset and persistence of PG are predicted by various prior DSM-IV anxiety, mood, impulse-control, and substance use disorders. PG also predicts the subsequent onset of generalized anxiety disorder, post-traumatic stress disorder, and substance dependence. Despite the high prevalence of PG, none of the NCS-R respondents with PG received treatment for gambling problems, but 49.0% were treated for other mental disorders. The study concludes that DSM-IV PG is a rare, impairing, and under-treated disorder, often co-occurring with other mental or substance disorders.