A large, integrated survey data set provided by the Ontario Problem Gambling Centre was used to investigate psychometric properties of the Problem Gambling Severity Index (PGSI). This nine-item self-report instrument was designed to measure a single, problem gambling construct. Unlike its nearest competitor--the South Oaks Gambling Screen (SOGS)--the PGSI was designed specifically for use with a general population rather than in a clinical context. The present analyses demonstrated that the PGSI does assess a single, underlying, factor, but that this is complicated by different, multiple factor structures for respondents with differing levels of problem gambling severity. The PGSI also demonstrated small to moderate correlations with measures of gambling frequency and faulty cognitions. Overall, the PGSI presents a viable alternative to the SOGS for assessing degrees of problem gambling severity in a non-clinical context.