RationaleTobacco use for many people is compulsive in nature. Compelling theories of how smoking becomes compulsive exist but are largely based on extrapolation from neuroscience findings. Research on smokers is impeded, in part, by a lack of instruments that specifically measure compulsive smoking.ObjectiveThis study evaluated the measurement structure and validity of the Obsessive Compulsive Smoking Scale (OCSS), a ten-item questionnaire designed to measure compulsive smoking.MethodsParticipants were 239 daily smokers (≥1 cigarette/day), including 142 students at a public university in Chicago and 97 veterans treated at the VA Boston Healthcare System. The OCSS and questionnaires measuring current and past smoking, cigarette craving, automatic smoking, and nicotine dependence were administered.ResultsFactor analysis with maximum likelihood extraction and oblique rotation revealed two correlated underlying factors, interpreted as “Preoccupation with Smoking” and “Compulsive Drive.” The measurement structure was consistent across students and veterans, and confirmed in an independent sample of adults (n = 95). Veterans exhibited higher OCSS scores (full scale and subscales) than students. Across groups, higher OCSS scores were positively correlated with smoking intensity, craving, and nicotine dependence. OCSS full-scale and compulsive drive scores, but not smoking preoccupation scores, were inversely correlated with past month smoking reduction and minutes since last cigarette.ConclusionsThe OCSS is a valid and reliable inventory for measuring the degree to which daily smokers are preoccupied with smoking and engage in compulsive tobacco use, and may be useful for advancing understanding of core smoking phenotypes or for tailoring cessation therapies.