The data for this research were collected in conjunction with the National Institute of Justice's ADAM (Arrestee Drug Abuse Monitoring) programs in Las Vegas, NV, and Des Moines, IA. Arrestees who had completed the ADAM interview and provided a urine specimen were then asked if they would be willing to answer an additional set of questions about their gambling behavior. Responses were recorded in the two study sites of six consecutive quarters, beginning in the fourth quarter of 1999. At the core of the 144-item gambling addendum was a modified version of the NORC DSM Screen (NODS), that assesses lifetime problem gambling and a corresponding set of items that assesses past-year gambling problems. The current study excluded the lifetime items. The Las Vegas sample consisted of 1,767 respondents, and the Des Moines sample numbered 540. Slightly more than 10 percent of the arrestees booked into Las Vegas detention facilities met the DSM-IV criteria for pathological gambling. In Des Moines, the prevalence rate was 4.4 percent. The most recent national survey (using the NODS screen) estimated the past-year prevalence rate of pathological gambling to be 0.6 percent. Arrestees who were pathological gamblers were no more likely to be arrested for serious crimes (felonies) than non-pathological gamblers, nor were they any more likely to be charged with income-generating crimes; however, they were significantly more likely than non-gamblers and most other gambling types to self-report committing assault, theft, or drug sales in the year prior to their current arrest. Generally, pathological gamblers were no more likely than non-pathological gamblers to test positive for illegal drugs. 18 tables, 51 references, and appended gambling addendum