The equilibrium and dynamic aspects of the dielectric behaviour of polymer systems are considered in macroscopic terms and molecular terms. The role of dipole moment correlations is considered for a model polyether series. It is suggested that studies of certain copolymers reveal that the reorientation term 〈µk(0). µk(t)〉 for a reference dipole in a polymer chain is not given by a simple exponential dependence upon time. A method is given for the evaluation of the macroscopic decay function from experimental dispersion and absorption data, and this is applied to the α relaxation in amorphous polyethyl acrylate.