In this paper a linearized version of an ‘ industrial dynamics ’ simulation mode discussed by Forrester (1061) is presented and analysed. It is shown that at least for the stop change in final demand treated by Forrester (19R1) the behaviour of the linearized model presented here is not dissimilar to the behaviour of Forrester's nonlinear model. Analysis of the linearized model shows that the poor transient behaviour of the system is due primarily to the modes associated with the exponential smoothing of the demand.