AbstractA stochastic model for the description, prediction and control of wastage in hierarchically structured manpower systems is given in this paper. In the model we identify reasons for leaving. When the expansion of the organization slows down people start to leave faster; conversely when expansion increases wastage tends to decrease. Thus the probabilities of individuals leaving voluntarily are not static. In this paper we model the phenomenon relating rates of voluntary leavers with the concept of cumulative acceleration of the overall growth of the organization. Results of testing the model in two large British firms are given.