A coherent exposition of the theory of scattering from a dynamic lattice, which applies to the scattering of Bloch-wave electrons as well as to the scattering of plane waves, is presented. This is achieved by developing a generalised diffraction model, along the lines conceived by Van Hove, appropriate for the scattering of Bloch waves. The resulting diffraction model provides a basis for treating processes controlled by electron-phonon interaction in general and subsumes the standard diffraction model results. The diffraction model origins of the standard approximate expressions used to describe electron-phonon interaction-controlled processes are also revealed.