We examined internal consistency and test-retest reliability of a measure of dispositional optimism, the Life Orientation Test-Revised, in 121 opiate-dependent patients seeking methadone treatment. Internal consistency was adequate at baseline (alpha = 0.69) and follow-up (alpha = 0.72). Low socioeconomic status and being on disability were significantly associated with reduced internal consistency; ethnic and educational differences approached significance. Test-retest reliability was good (ICC = 0.72), varying across gender, race, ethnicity, education, employment and income (ICC Range = 0.24-0.85). Criterion validity was strong; the LOT-R was significantly negatively correlated with hopelessness (r = -0.65, p less than 0.001) and depression (r = -0.60, p less than 0.001). Findings support the use of this measure of optimism and pessimism to assess positive cognitive and emotional attributes and improve treatment strategies for opiate-dependent individuals. Future research should address the measurement and significance of optimism in minority, low socioeconomic status and poorly-educated individuals.