Reduced physical function and health-related quality of life are common in rheumatoid arthritis (RA), and further studies are needed that examine novel determinates of reduced physical function in RA. This study examines whether frailty, a state of increased vulnerability to stressors, is associated with differences in self-reported physical function among adults with RA. Adults from a longitudinal RA cohort (n = 124) participated in the study. Using an established definition of frailty, individuals with three or more of the following physical deficits were classified as frail: (1) body mass index <= 18.5, (2) low grip strength (adjusted for sex and body mass index (BMI), measured by handheld dynamometer), (3) severe fatigue (measured by the Multidimensional Assessment of Fatigue), (4) slow 4-m walking speed (adjusted for sex and height), and (5) low physical activity (measured by the International Physical Activity Questionnaire). Individuals with one or two deficits were classified as "pre-frail" and those with no deficits as "robust." Self-reported physical function was assessed by the Health Assessment Questionnaire (HAQ) and the Valued Life Activities Difficulty scale. Regression analyses modeled associations of frailty category with HAQ and Valued Life Activities (VLA) Difficulty scores with and without controlling for age, sex, disease duration, C-reactive protein, use of oral steroids, and pain. Among adults with RA, being frail compared to being robust was associated with a 0.44 worse VLA score (p < 0.01) when the effects of covariates are held constant. Being frail, compared to being robust, is associated with clinically meaningful differences in self-reported physical function among adults with RA.