Stratospheric zonal wind values are used in conjunction with operationally produced tropospheric data and contemporaneous earth rotation data to study the angular momentum budget of the global atmosphere-earth system on seasonal time scales. Previous imbalances found in this budget at the semiannual period are considerably reduced with the inclusion of the stratospheric data. At the annual period the momentum contained in stratospheric winds also appears large enough to account for the previous discrepancies, although there is more uncertainty at this period because of the sizeable disagreements that exist between the tropospheric time series. Despite this and the limitation of our study to a 2-year sample, our results nevertheless suggest that tropospheric plus stratospheric winds can fully account for seasonal, nontidal changes in the length of day without invoking other geophysical processes. The amplitude and phase of the seasonal components of momentum fluctuations within the stratosphere resemble those which can be inferred from some earlier studies. Annual variations in the stratosphere's globally integrated momentum result from opposing contributions by the two hemispheres. Semiannual variations in this quantity result mainly from behavior in the tropics.