In this paper, the one-dimensional quasi-linear instability of electron plasma waves considered by Drummond and Pines is calculated with allowance for spontaneous emission. If the initial electron plasma wave spectrum is assumed to be in equilibrium with the thermal electrons the spontaneous emissive power is inversely proportional to the number N of electrons in the Debye volume. For N ≲ 103, it is found that the spontaneous emission drives the instability to overcome the quasi-linear asymptotic state, which is recovered for larger N if the initial values used by Drummond and Pines are applied. Connections between the one-dimensional problem and the physical problems entailed by more dimensions are discussed.