OBJECTIVE: Support for the reliability and validity of the Medical Outcomes Study (MOS) Sleep Scale was provided in the MOS sample of 3,445 individuals with chronic illness. We sought to extend this work by evaluating the psychometric properties of the MOS-Sleep Scale in the US general population. METHODS: The MOS-Sleep Scale is a 12-item, self-reported survey that yields six subscales: sleep disturbance, snoring, awaken short of breath or with headache, quantity of sleep, sleep adequacy, and somnolence as well as a nine-item sleep problem index. The subscales and problem index are scored on a 0 to 100 range, with higher scores indicating more of the domain being measured. We administered the MOS measure by telephone to a nationally representative sample of 1011 U.S. adults aged 18 and older in January 2001. RESULTS: The average age of the sample was 46; 51% were female and 74% were white. Internal consistency reliability estimates for the MOS-Sleep scales tended to be adequate: sleep disturbance (4 items, alpha = 0.80); sleep adequacy (2 items, alpha = 0.82); sleep somnolence (3 items, alpha = 0.63); and nine-item sleep problems index II (alpha = 0.83). Adjusting for age and gender, MOS patients reported significantly more quantity of sleep (t = 3.27, P < .002), but significantly worse sleep disturbance (t = 5.08, P < .001), snoring (t = 2.16, P < .05), shortness of breath (t = 4.59, P < .001), sleep adequacy (t = -2.39, P < .05), somnolence (t = 5.10, P < .001), and sleep problems (t= 3.27, P < .002) than the general U.S. population. CONCLUSIONS: The MOS-Sleep Scale was found to have good internal consistency reliability and to discriminate between patients with chronic illness and the U.S. general population. Further work is needed to compare the MOS-Sleep Scale results with objective measures of sleep such as polysomnography. Session IV Mental Health II