In N2 (and in N2 with a small amount of CH4) electron avalanches and their development into the generation mechanism were investigated at μ⋛ 1 in a pulsed homogeneous electrical field. The temporal development of the avalanche currents was measured by photomultiplier techniques. The avalanches were started by a high number of electrons (≅ 103), released at the cathode by a short light flash; thus the discharge currents were free from statistical fluctuations. — The comparison of measured and calculated current shapes of the generation mechanism show good agreement. The influence of the positive ion space charge on the development of the discharge current is demonstrated. At higher overvoltages (> 20%) streamer mechanism is found; in a transition region (≅17%) both mechanism (streamer- and generation mechanism) are observed as concurring processes.