A coordinated rocket experiment measuring the red line of atomic oxygen at 6300 ¿, the photoelectron flux, and the ionospheric densities of O2+ and ne was flown into the twilight mid-latitude airglow over White Sands, New Mexico. Analysis of the 6300-¿ emission rate profile shows that photoelectron impact excitation of atomic oxygen is the main source of 0(1D) atoms above 240 km; the rate of this source at 265 km is 9.8¿10-8 s-1. Photodissociation of O2 in the Schumann-Runge continuum is the main source of 0(1D) atoms below 200 km. A value of 02 dissociation rate for the unattenuated solar flux of 2.2¿10-6 s-1 best fits the observations. Dissociative recombination of 02+ ions is important above 200 km, and the dissociative recombination rate coefficient derived from the measurement is (2.4¿1.2) ¿10-8 cm3 s-1. With the model N2 densities used in the calculation the quenching rate coefficient was found to be lower than values previously used in similar calculations.