A simple quantitative formulation of transit‐time‐limited wall motion is used to show that such an effect can reasonably explain the observed nonlinear wall motion in Permalloy thin films. The ``critical velocity'' is calculated by equating the intrinsic relaxation timeTito the transit timeTtfor the wall past an individual spin position to obtainVcrit=&dgr;/Ti, where &dgr; is the wall width. The model correctly predicts (i) the magnitude and (ii) variation with film thickness of the observed knee in the velocity‐field curves for wall motion in Permalloy films.