The Arecibo 430 MHz radar has been used to measure D region Thomson scatter power spectra which display bandwidth and power variations with altitude and solar zenith angle which are consistent with the presence of negative ions. The negative ion-to-electron number density ratio (&lgr;-)s, electron density, and electron-to-ion temperature ratio (Te/Ti) have been derived from the spectral data and presented for noontime and sunset conditions. The &lgr;-=1 level is found to occur near 70 km at noon and near 80 km at sunset. Values of Te/Ti in the range 1.0 to 1.5, due to probing pulse heating, were observed.