The entrainment and drainage of particles in a flotation froth have long been recognised as important factors affecting both concentrate grade and recovery. In this paper,an empirical partition curve is proposed that describes the degree of entrainment within a conventional flotation cell. Two empirical parameters are defined: entrainment parameter (xi)-the particle size for which the degree of entrainment is 20%. drainage parameter (delta)-related to the preferential drainage of coarse particles. The model is flexible enough to fit a broad data set published in the flotation literature. Results from a case study indicate that the model is sufficiently detailed to describe the entrainment and drainage mechanisms. This being so, the effect of process variables which affect the degree of entrainment can he properly quantified and then included in a simulation package, assisting in the optimisation of existing flotation circuits and the design of future ones.