Functional status questionnaires are being used in various types of studies. To determine factors related to self‐reported functional ability for rheumatoid arthritis patients, we examined the relationship between a functional and mental health questionnaire and objective disease‐specific measures. Using 3–5 predictor variables, we explained 43–57% of the variance in patients' self‐reported functioning. Mental and physical health perceptions were significant predictors for each self‐reported functional measure. The relationships among mental health and self‐reported functioning should be considered when interpreting studies that use functional status questionnaires.