Nonlinear plasma oscillations in a classical, nonrelativistic, collisionless, Maxwellian electron gas are considered. There is assumed a small, sinusoidal variation in the spatial part of the initial distribution function, corresponding to excitation of wavenumber modes ±k0. The nonlinear Vlasov equation is solved to third order in the long time limit via the Montgomery‐Gorman perturbation expansion, where the expansion parameter is &egr;, the amplitude of the initial perturbation. The linear, first‐orderk0mode of the electric field is dominated by the Landau solution with (negative) damping decrement &ggr;L. The third‐orderk0mode is modified, however, by singling out the spatially uniform part of the distribution function for special treatment, much in the manner of the quasi‐linear theory. A nonlinear damping decrement results such that, for many values ofk0and &egr;, &ggr;L< &ggr;N. Thus at sufficiently long times, the modified third‐order mode dominates the solution. For certain &egr; andk0this behavior resembles the results of Knorr and Armstrong, obtained by numerical integration of the nonlinear Vlasov equation.