We propose to continue for three more years the research program currently supported by NSF Grant ATM-8721669. Most of the work will fall into one of three areas: (1) incoherent scatter research, particularly at high altitudes, (2) auroral radar studies, and (3) studies of temperate latitude E-region plasma instabilities similar to those seen at the equator, and perhaps also temperate latitude spread F. Some effort may also be devoted to PMSE (polar mesospheric summer echoes) research. In most of these areas an active research program is already underway; in some cases the program has existed for a number of years and has produced a substantial scientific return.