AIMS To assess the measurement properties of the 10 symptoms of pathological gambling defined by the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) in a general population survey, including examination of unidimensionality and relative severity of the symptoms and their typical patterning. DESIGN We conducted a Rasch model item-response analysis of data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). SETTING The NESARC surveyed a nationally representative sample from the United States. PARTICIPANTS Participants were 11 153 individuals who reported gambling more than five times in a single year. MEASUREMENTS The NESARC survey employed the Alcohol Use Disorder and Associated Disability Interview Schedule-DSM-IV version (AUDADIS-IV). FINDINGS AND CONCLUSIONS DSM-IV problem gambling symptoms were strongly unidimensional and maintained a reliable ordering across a broad range of the problem gambling continuum, indicating that the 10 symptoms can be used to create an additive index of problem severity. The DSM-IV-based symptom index appeared to have sufficient reliability to separate life-time pathological gamblers from other gamblers using the current diagnostic threshold of five or more symptoms. However, the DSM-IV symptom index did not have sufficient reliability to separate further among groups of gamblers who reported fewer than five symptoms. After equating for the level of gambling problem severity, the likelihood of reporting certain symptoms was biased across groups characterized by their age and gender. Implications for understanding the construct of gambling problems severity and use of symptom counts as a continuous index are discussed.