Although Gamblers Anonymous (GA) is a popular intervention for gamblers, many attendees later present for professional treatment. This study evaluated gambling and psychosocial problems in individuals seeking professional treatment for gambling and compared those with and without a history of GA attendance. At intake to treatment, 342 pathological gamblers completed the Addiction Severity Index (ASI) and South Oaks Gambling Screen (SOGS). Fifty-four percent attended GA previously. Compared to non-GA attendees, GA attendees were older, had higher incomes, and were less likely to be single. They had higher SOGS scores, more years of gambling problems, and larger debts. GA attendees also had more serious family conflicts and less serious drug problems. Individuals with a history of GA attendance were more likely to be abstinent from gambling 2 months after treatment initiation. Logistic regression revealed that the number of professional sessions and GA meetings attended during treatment was independently associated with short-term abstinence. These data suggest that individuals entering professional treatment for gambling with a history of GA attendance differ from those who do not, and these differences may impact treatment recommendations and outcomes.