A systematic methodology that facilitates the modelling of a non-linear dynamic system for the purposes of controller design is described and applied to the forced Van der Pol oscillator. The non-linear model is represented as a set of linear time-invariant models. This results in a nominal linear model with a quantified parameter uncertainty. This information is applied in conjunction with the quantitative feedback theory (QFT)control design method to produce a controller which meets the performance specifications. The controller is verified with non-linear simulation and experimentation. The method reduces the number of iterations required to design practical controllers for non-linear systems considerably compared with trial and error methods.