Cross sections for single ionization and for combined dissociative and double ionization of N/sub 2/ by electron impact were measured using a crossed- beam technique. The data obtained are analyzed, and the dissociative ionization processes are discussed. It is concluded that dissociative ionization is not likely to result from a single interaction at electron energies less than about 45 ev. A probable explanation of the sizable N plus or minus currents found below 40 ev in mass spectrometers is given. (H.D.R.)