A unified approach to the cluster expansion of the ground-state energy of a system whose wave function is a product of two factors, one of which is a Jastrow function, is presented. It is shown that several previously derived expansions, notably those of Wu and Feenberg and of Massey and Woo, are special cases of this one. The most general case of this expansion, when applied to crystalline helium, incorporates “self-consistent” phonons, exchange, and the Massey-Woo treatment of short-range correlations.