In principle, a single equation can be derived which describes densification through all stages of sintering, if (a) the kinetics of mass transport which lead to densification can be expressed mathematically and (b) the microstructure can be quantified to embody both (i) its tendency to generate mass flows which contribute to densification, and (ii) the efficiency at which such flows are converted into shrinkage. To satisfy condition (a), it will be assumed at the outset that only capillarity-induced diffusional mass flows contribute to densification. (It is not the purpose of the present paper to discuss the multidecade debate on the role of dislocations in sintering. Any demonstrated sintering rates greater than those predicted by this model may be discussed in terms of dislocation motion or other enhancements.) Therefore, the challenge to developing a combined-stage sintering model is to find a method for correctly quantifying the complex changes in microstructure which occur during sintering.