Objective: This longitudinal study examined the unique relationship between anxiety, symptoms (pain intensity, sleep disturbance, fatigue severity), and function domains (self-reported cognitive function, physical function, satisfaction with social roles) in individuals with chronic physical conditions, independent of depressive symptoms. Method: Three surveys were mailed on an approximately yearly basis to community-dwelling adults with one of four chronic physical conditions (spinal cord injury, multiple sclerosis, muscular dystrophy, postpoliomyelitis syndrome). The first survey was completed by 1594 individuals (T1). Of these, 1380 completed the second survey (T2), and 1272 completed the third survey (T3). Results: Mixed growth curve models evidenced significant concurrent and longitudinal associations between anxiety and each symptom and function domain, independent of depression severity. The largest unique association found was between anxiety and self-reported cognitive function; inclusion of the measure of anxiety in the model improved model fit substantially over depression alone, χ2 = 104.40, p < .001. Both anxiety and depression exhibited similar effect sizes in their unique relationships with each symptom and function domain measure. However, depression was more strongly associated with satisfaction with social roles and physical function than was anxiety. Conclusions: The findings showed that anxiety assessed at one point in time demonstrated significant and unique associations with concurrent and subsequent symptom and function domains. Given that anxiety has been inadequately studied (and perhaps evaluated and treated) in rehabilitation populations, the current findings suggest that researchers and clinicians should broaden their scope when assessing and treating psychological distress to incorporate anxiety and related disorders.