OBJECTIVES:To examine the longitudinal association between decline in physical function and risk of elder abuse. DESIGN:Prospective population-based study. SETTING:Geographically defined community in Chicago. PARTICIPANTS:One hundred forty-three Chicago Health and Aging Project (CHAP) participants who had elder abuse reported to a social services agency from 1993 to 2010 were identified. PARTICIPANTS:The primary independent variable was objectively assessed physical function using decline in physical performance testing (tandem stand, measured walk, and chair stand). Secondary independent variables were assessed using decline in self-reported Katz, Nagi, and Rosow-Breslau scale scores. Dependent variables were reported and confirmed elder abuse and specific subtypes of elder abuse (physical, psychological, caregiver neglect, and financial exploitation). Logistic regression models were used to assess the association between decline in physical function measures and risk of elder abuse. RESULTS:After adjusting for potential confounders, decline in physical performance testing (odds ratio (OR) = 1.13, 95% confidence interval (CI) = 1.06-1.19), Katz impairment (OR = 1.29, 95% CI = 1.15-1.45), Nagi impairment (OR = 1.30, 95% CI = 1.13-1.49), and Rosow Breslau impairment (OR = 1.42, 95% CI = 1.15-1.74) was associated with greater risk for elder abuse. The lowest tertile of physical performance testing (OR = 4.92, 95% CI = 1.39-17.46) and the highest tertiles of Katz impairment (OR = 3.99, 95% CI = 2.18-7.31), Nagi impairment (2.37, 95% CI = 1.08-5.23), and Rosow Breslau impairment (OR = 2.85, 95% CI = 1.39-5.84) were associated with greater risk of elder abuse. CONCLUSION:Decline in objectively assessed physical function and self-reported physical function are associated with greater risk for elder abuse.