To test whether 2 conceptually overlapping constructs, dispositional optimism (generalized positive expectations) and optimistic bias (inaccurately low risk perceptions), may have different implications for smoking treatment engagement. Predominantly Black, low-income Southern Community Cohort study smokers (n = 880) self-reported dispositional optimism and pessimism (Life Orientation Test-Revised subscales: 0 = neutral, 12 = high optimism/pessimism), comparative lung cancer risk (Low/Average/High), and information to calculate objective lung cancer risk (Low/Med/High). Perceived risk was categorized as accurate (perceived = objective), optimistically-biased (perceived < objective), or pessimistically-biased (perceived > objective). One-way ANOVAs tested associations between dispositional optimism/pessimism and perceived risk accuracy. Multivariable logistic regressions tested independent associations of optimism/pessimism and perceived risk accuracy with cessation motivation (Low/High), confidence (Low/High), and precision treatment attitudes (Favorable/Unfavorable), controlling for sociodemographics and nicotine dependence. Mean dispositional optimism/pessimism scores were 8.41 (SD = 2.59) and 5.65 (SD = 3.02), respectively. Perceived lung cancer risk was 38% accurate, 27% optimistically-biased, and 35% pessimistically-biased. Accuracy was unrelated to dispositional optimism (F(2, 641) = 1.23, p = .29), though optimistically-biased (vs. pessimistically-biased) smokers had higher dispositional pessimism (F(2, 628) = 3.17, p = .043). Dispositional optimism was associated with higher confidence (Adjusted odds ratio [AOR] = 1.71, 95% CI [1.42, 2.06], p < .001) and favorable precision treatment attitudes (AOR = 1.66, 95% CI [1.37, 2.01], p < .001). Optimistically-biased (vs. accurate) risk perception was associated with lower motivation (AOR = .64, 95% CI [.42, .98], p = .041) and less favorable precision treatment attitudes (AOR = .59, 95% CI [.38, .94], p = .029). Dispositional optimism and lung cancer risk perception accuracy were unrelated. Dispositional optimism was associated with favorable engagement-related outcomes and optimistically-biased risk perception with unfavorable outcomes, reinforcing the distinctiveness of these constructs and their implications for smoking treatment. (PsycInfo Database Record (c) 2022 APA, all rights reserved).