AIMS: To help refine the definition and diagnosis of gambling disorders, we investigated the distribution among US gamblers of the 10 DSM-IV criteria for Pathological Gambling. DESIGN: We drew data from two stratified random surveys (n = 2417, n= 530) of gambling behavior and consequences among community-based samples of US adults. A fully structured questionnaire, administered by trained lay interviewers, screened for the life-time prevalence of problem and Pathological Gambling. Per DSM-IV definitions, anyone meeting five or more of 10 itemized criteria was considered a pathological gambler. We analyzed these criteria among all gamblers who met one or more criteria (n = 399). FINDINGS: Most gamblers who met only one or two criteria reported 'chasing their losses'. At subclinical levels (three to four criteria), gamblers also reported elevated rates of gambling-related fantasy: lying, gambling to escape and preoccupation. Pathological gamblers with five to seven criteria reported marked elevations of loss of control, withdrawal symptoms and tolerance (internalizing dimensions of dependence); risking their social relationships and needing to be bailed out financially (externalizing dimensions). Most of the highest-level pathological gamblers (eight to 10 criteria) reported committing illegal acts to support gambling. CONCLUSION: Dependence in a biobehavioral sense appears to be a hallmark of Pathological Gambling, but it marks only one threshold in a qualitative hierarchy of disorders beginning with a common subclinical behavior, 'chasing'. Epidemiological assessments and future DSM revisions might consider explicit recognition of a problem gambling disorder, identifying people presenting some cognitive symptoms of Pathological Gambling but not clear signs of dependence. Pathological gamblers in turn appear to have two distinct levels of severity.