Distribution functions describing the correlation between the positions and orientations of groups of one, two, three, …, molecules are defined and discussed. The one-particle distribution function of an anisotropic fluid—such as a liquid in a uniform field—is expanded in orthogonal functions S that are simply related to the mean values of the Legendre polynomials describing its orientation. A variety of observables, including dielectric polarization, optical birefringence, Rayleigh and harmonic scattering, and magnetic resonance spectra, are described in terms of the appropriate S-coefficients and the orientation distribution functions.