The aging suppressor gene klotho encodes a single-pass transmembrane protein klotho that in mice is known to extend life span when overexpressed and to resemble accelerated aging, with skeletal muscle atrophy and decreased bone mineral density, when expression is disrupted. We sought to examine the relationship between plasma klotho and disability in activities of daily living (ADL) in older community-dwelling adults. In a cross-sectional study, plasma klotho was measured in a population-based sample of 802 adults, ≥ 65 years, who participated in the "Invecchiare in Chianti" (Aging in the Chianti Area) (InCHIANTI) study in Tuscany, Italy. The overall proportion of adults with ADL disability was 11.9%. Mean (standard deviation) klotho concentrations were 689 (238) pg/mL. From the lowest to the highest tertile of plasma klotho, 16.1%, 9.7%, and 5.6% of participants, respectively, had ADL disability (p=0.0004). Plasma klotho, per 1 standard deviation increase, was associated with ADL disability (odds ratio=0.57, 95% confidence interval 0.35-0.93, p=0.02) in a multivariate logistic regression model adjusting for age, education, cognition, physical activity, physical performance, total cholesterol, alcohol and tobacco use, and chronic diseases. Low plasma klotho concentrations were independently associated with ADL disability among older community-dwelling men and women.