BACKGROUND: Chronic pain is associated with significant physical and psychological impairments across the adult lifespan. However, there is a relative gap in knowledge on individual differences that predict pain-related functioning. The current study highlights one important source of individual variation: age. METHODS: We used cross-sectional data from a large treatment-seeking cohort of 2,905 adults (M age = 46.6 [13.1]; 71.8% women) presenting to a tertiary pain centre in the United Kingdom to determine age differences in cognitive-affective processes (catastrophizing, acceptance, self-efficacy), including their differential patterns and effects on disability and depression. RESULTS: Older adults (ages 65-75) were found to experience higher pain acceptance and pain self-efficacy compared to both middle-aged (ages 40-64) and young adult (ages 18-39) age groups. Older adults also experienced lower levels of catasophizing compared to middle-age adults. Testing age as a moderator, we found that the relationships of pain self-efficacy and acceptance with depression as well as the relationship between pain self-efficacy and disability were comparatively weakest among older adults and strongest among young adults. Similarly, the relationship between pain catastrophizing and depression was relatively stronger for young and middle-aged adults compared to older adults. CONCLUSIONS: Age-related differences in psychological mechanisms that influence pain-related functioning present unique challenges and opportunities for scientists and clinicians to improve our understanding and treatment of pain across the lifespan. Additional work is needed to refine our knowledge of age-related differences in cognitive-affective, biopsychosocial dimensions of chronic pain and to develop and test the efficacy of age-tailored interventions. SIGNIFICANCE: Our cross-sectional analysis of 2,905 treatment-seeking adults with chronic pain presenting to a tertiary care center in the United Kingdom revealed distinct age differences in cognitive-affective linked to disability and depression. This study contributes to the limited knowledge on age-related variance in psychological mechanisms underlying adjustment to chronic pain. Promising avenues for future research include refining our understanding of age-related differences in cognitive-affective, biopsychosocial dimensions of chronic pain and elucidating the most salient treatment targets among different age groups.