The primary goal of the study was to compare adult age groups on aging bias, with measures of knowledge of aging in the physical, psychological, and social domains and life satisfaction. The study sample, consisting of 752 men and women, 40 to 95 years of age, was tested using Neugarten, Havighurst, and Tobin's (1961) Life Satisfaction Index (LSI) and Palmore's Facts on Aging Quiz (1998) modified to extract bias toward older adults and categorized into 3 domains: physical, psychological, and social. Independent variables were 3 levels of LSI from the Neugarten et al. quiz. Aging bias was measured among the age groups, gender, life satisfaction, and knowledge of aging domains. Significant bias differences were found in age group, life satisfaction, and knowledge of aging domain variables. Financial, health, and volunteer status interacted with these effects. Among other significant findings, the data indicate that middle-aged adults 40-59 have the most negative bias in the psychological and social domains and the least negative bias in the physical domain compared to the older participants. Both middle aged and old-old adults have the most negative aging biases. These differential aging stereotypes (positive and negative) among the physical, psychological, and social perceptions of aging over adult age groups are interpreted within aging stereotyping and aging self-stereotyping. (Contains 3 figures and 3 tables.)