Equations have been derived which describe the nonlinear evolution of standard drift waves (driven by inverse Landau damping) and of dissipative trapped electron modes. Assuming that all but then=0 modes are shear stabilized, it is shown that the nonlinear equations admit eigenfunctions of the same form as the linear equations with, however, the shear lengthLs=q/(&egr;dlnq/dr) replaced by another lengthls<Ls.lsdecreases with increasing turbulence thereby stabilizing the mode. The turbulence level and the diffusion coefficient are self‐consistently calculated. In the case of the standard drift wave, good agreement is found with experimental results in linear devices. In the case of the trapped electron mode, estimates obtained with parameters derived from published profiles of ST tokamak discharges are quite reasonable. Stabilization arises through nonlinear diamagnetic drifts.