The effect of positioning (sitting and prone standing) on the hand function of 10 boys (mean age = 12.5 years, SD = 1.2 years) with spastic diplegic cerebral palsy was studied. Two groups of subjects were tested twice (Tests 1 and 2) with the Jebsen-Taylor Hand Function Test (Jebsen, Taylor, Treischmann, Trotter, & Howard, 1969; Taylor, Sand, & Jebsen, 1973) to measure rate of manipulation. In addition, a scale modified from Hohlstein (1982) was used to measure quality of grasp on each subtest of the Jebsen-Taylor test. No significant differences between the mean scores of the two groups were found on the total scores of the Jebsen-Taylor test, either between Tests 1 and 2 or between sitting and prone standing. When the data from Tests 1 and 2 were combined, it was found that on one subtest–simulated feeding–the subjects performed significantly faster while in a prone standing position. On another subtest–picking up small objects–the subjects performed significantly faster while in a sitting position. Except during the simulated feeding subtest, the quality of the subjects’ grasp was observed to be mature and tailored to the objects manipulated. This paper presents considerations for analyzing positioning in relation to upper extremity tasks.