The understanding of wave and wave-dissipative processes in the MLT region has increased remarkably over the past four years and a healthy mix of experimental and theoretical work is being carried out. Sustained theoretical work has led to quantitative prescriptions for the effects of waves on the general circulation and energetics. Significant new insights into the way in which the atmosphere responds on a global basis are coming from the UARS mission, with important new constraints on tidal phases and amplitudes becoming available. It is to be expected that the next few years will bring continued progress, as various coordinated ground-based experimental campaigns come to fruition, as the UARS data base is fully analyzed, and as the theoretical models develop. The exciting prospect of a dedicated NASA TIMED mission, supported by a coordinated array of ground-based observations and theory also lies ahead.
Acknowledgments. This work was supported by NASA grants NAGW-3457 and NAG1-1315 and by NSF grants ATM-9308157, ATM-9301867 and ATM-9400877 to the University of Michigan.