Environmental, interpersonal, and psychological factors contribute to gambling, but no standardized instrument for assessing high-risk gambling situations exists. This study evaluates the factor structure of the Inventory of Gambling Situations (IGS), a newly developed measure to examine situations that precipitate gambling. Pathological gamblers (n = 233) beginning a treatment study completed the IGS. Principal component analysis revealed that a 5-factor solution best fit the data, representing items related to Negative Affect, Luck and Control, Positive Affect, Social Situations, and Gambling Cues. Overall, Cronbach α was 0.960, ranging from 0.820 to 0.935 for the 5 factors. IGS scores correlated with other indices of gambling problems. Women scored higher on the Gambling Cues factor than men, and younger respondents, regardless of gender, scored higher on the Luck and Control factor than older respondents. The IGS may assist in better understanding situations in which pathological gamblers wager, and individual differences with respect to these situations.