A comprehensive study of the ionospheric D and E regions of the atmosphere is the central theme in this study. The experimental work will utilize both the radar and optical facilities at the Arecibo Observatory with data analysis and theoretical work carried out at Penn State University. Specific studies will involve the chemistry and dynamics of the mesopause OH emission region, formation and transport of "sporadic" layers of ionization and involvement in a multi-instrumented campaign (AIDA) at Arecibo, with planning for an in-depth multi- instrumented coordinated rocket program associated with the D and E regions.