This study demonstrated the development of a measurement model for gross upper-extremity function (GUE). The dependent variable was the Rasch calibration of the 27 ICF-GUE test items. The predictors were object weight, lifting distance from floor, carrying, and lifting. Multiple regression was used to investigate the contribution that each independent variable makes to the model with 203 outpatients. Object weight and lifting distance were the only statistically and clinically significant independent variables in the model, accounting for 83% of the variance (p < 0.01). The model indicates that, with each one pound increase in object weight, item challenge increases by 0.16 (p < 0.00) logits, and with each one inch increase in distance lifted from floor, item challenge increased by 0.02 logits (p < 0.02). The findings suggest that the majority of the variance of the measurement model for the ICF-GUE can be explained by object weight and distance lifted from the floor.