Objectives: This study investigated the role of response style biases in the assessment of positive and negative affect in aging research; it addressed whether response styles (a) are associated with age-related changes in cognitive abilities, (b) lead to distorted conclusions about age differences in affect, and (c) reduce the convergent and predictive validity of affect measures in relation to health outcomes. Method: A multidimensional item response theory model was used to extract response styles from affect ratings provided by respondents to the psychosocial questionnaire (n = 6,295; aged 50-100 years) in the Health and Retirement Study (HRS). Results: The likelihood of extreme response styles (disproportionate use of "not at all" and "very much" response categories) increased significantly with age, and this effect was mediated by age-related decreases in HRS cognitive test scores. Removing response styles from affect measures did not alter age patterns in positive and negative affect; however, it consistently enhanced the convergent validity (relationships with concurrent depression and mental health problems) and predictive validity (prospective relationships with hospital visits, physical illness onset) of the affect measures. Discussion: The results support the importance of detecting and controlling response styles when studying self-reported affect in aging research.