Return to work following treatment for a work-related upper extremity disorder (WRUED) is affected by a variety of medical, workplace, and personal factors, and returning to modified duty may ease the transition to normal work activities. This study surveyed 165 federal government employees (127 females, 38 males) who were unable to resume their normal work after filing a workers' compensation claim for a WRUED (<90 days from claim filing) and who volunteered for a randomized study of alternative case management strategies. Before randomization, participants completed a baseline survey of upper extremity (UE) symptoms, functional limitations, and workplace factors. At baseline, 58 participants (35%) were working modified duty and 107 participants (65%) were not working. Compared with participants working modified duty, those who were not working were more likely to report: (a). a diagnosis of mononeuropathy, odds ratio (OR)=3.16 (95% confidence interval (CI)=1.37-7.14) versus enthesopathy, (b). higher pain ratings, OR=1.43 (95% CI=1.01-2.01), (c). greater functional limitations, OR=1.63 (95% CI=1.11-2.38), and (d). higher level of ergonomic stressors, OR=1.62 (95% CI=1.09-2.43) in a multivariable logistic regression. Measures of high risk work styles (fast pace and working despite pain) were associated with greater perceptions of ergonomic exposure, but not with work status. The model had 87.9% sensitivity and 43.1% specificity to correctly classify those not working (overall classification 72.1% correct). The results suggest that modified duty for workers with persistent WRUEDs may be enhanced by assessing perceived functional limitation and ergonomic exposure as well as the type and severity of symptoms.