Physical fatigability, or susceptibility to physical fatigue, is strongly associated with aging, disease, and disability. Over the lifecourse, personality traits are also connected to numerous age-related vulnerabilities and resistance-yet, their longitudinal association with fatigability remains unknown. Well-functioning community-dwelling volunteers aged ≥50 (N = 995) from the Baltimore Longitudinal Study of Aging (BLSA) were assessed over an average of 2 years on personality traits (NEO-PI-R; openness, conscientiousness, extraversion, agreeableness, and neuroticism) and perceived fatigability [Borg Rating of Perceived Exertion (RPE) after a 5-min slow treadmill walk; 6 (low) to 20 (high) exertion]. Linear and multinomial logistic regression models examined cross-sectional associations [treating fatigability continuously and by RPE category: low (6-7), intermediate (8-9), and high (10+)]. Generalized estimating equations (GEE) tested longitudinal associations. All models were adjusted for demographics and comorbid conditions. In cross-sectional models, openness, β = -.09 RPE (SE =.03); p < .01, conscientiousness, β = -.07 (.03); p < .05, and extraversion, β = -.10 (.03); p < .01, were negatively associated with fatigability. In parallel, lower openness, OR: .98, 95% CI [.96-1.00], conscientiousness, OR: .98, 95% CI [.96-1.00], and extraversion, OR: .97, 95% CI [.95-.99], corresponded with higher odds of having high versus low fatigability. In longitudinal models (mean follow-up time 2 ± 2 years), openness, conscientiousness, and extraversion associations remained significant and did not change over time (Trait × Year p values > .34). Together, findings suggest that personality plays a role in the perceived tolerance of fatigue in well-functioning older adults. (PsycInfo Database Record (c) 2021 APA, all rights reserved).