Electron impact excitation of the b1&Pgr;u state in N2 plays a prominent role in the dissociation of the molecule and thus in the production of atomic nitrogen in planetary atmospheres. Electron impact excitation cross sections combined with electron-impact-induced fluorescence measurements can yield the corresponding dissociation cross sections. Serious discrepancies exist among excitation cross sections reported in the literature. To clarify the situation, we measured these cross sections at two impact energies using electron energy loss spectroscopy. The new results are in agreement with recent values deduced from optical measurements and fall midway between previous results which are too high or low by factors of 2. ¿ American Geophysical Union 1991