BACKGROUND: New strategies to increase physical activity among sedentary older adults are urgently needed. OBJECTIVE: To examine whether low expectations regarding aging (age-expectations) are associated with low physical activity levels among older adults. DESIGN: Cross-sectional survey. PARTICIPANTS: Six hundred and thirty-six English- and Spanish-speaking adults aged 65 years and above attending 14 community-based senior centers in the Los Angeles region. Over 44% were non-Latino whites, 15% were African American, and 36% were Latino. The mean age was 77 years (range 65 to 100). MEASUREMENTS: Self-administered written surveys including previously tested measures of age-expectations and physical activity level in the previous week. RESULTS: Over 38% of participants reported <30 minutes of moderate-vigorous physical activity in the previous week. Older adults with lower age-expectations were more likely to report this very low level of physical activity than those with high age-expectations, even after controlling for the independent effect of age, sex, ethnicity, level of education, physical and mental health-related quality of life, comorbidity, activities of daily living impairment, depressive symptoms, self-efficacy, survey language, and clustering at the senior center. Compared with the quintile of participants having the highest age-expectations, participants with the lowest quintile of age-expectations had an adjusted odds ratio of 2.6 (95% confidence intervals: 1.5, 4.5) of reporting <30 minutes of moderate-vigorous physical activity in the previous week. CONCLUSIONS: In this diverse sample of older adults recruited from senior centers, low age-expectations are independently associated with very low levels of physical activity. Harboring low age-expectations may act as a barrier to physical activity among sedentary older adults.