The organization and structuring of spontaneous arm movements of 8 neonates were studied quantitatively. The movements were divided up into units, each consisting of 1 acceleration and 1 deceleration phase. This analysis showed that the movements had a distinct temporal structuring. An analysis of curvature was also performed, and it showed that the most distinct changes in movement direction occurred at the transitions between movement units. Finally, the movements of the 2 arms were found to be coupled in all 3 dimensions of space. They had a clear tendency to move together along the body's longitudinal axis, abduct and adduct together, and extend together in the forward direction.