This article presents the development and validation of the aging stereotypes and exercise scale (ASES), which measures different dimensions of aging stereotypes in the exercise domain. Drawing on past research on older adults' perceived barriers to exercise, these dimensions include stereotypes about positive and negative exercise outcomes for older adults and about older adults' psychological barriers to exercise (i.e., lack of self-efficacy and motivation). Four studies involving 714 participants examined the factorial structure and invariance, temporal stability, and external validity of the scale. The results supported a 3-factor model that was invariant across age. Age differences in stereotype content appeared, with older adults holding more positive stereotypes than younger adults. Also as predicted, the more older adults endorsed negative stereotypes, the lower their physical self- worth, self-rated health, and subjective age. Last, responses to the ASES appeared to be stable over a 6-wk period.