A new theory of the thermodynamics and structure of polymer-chain fluids is developed. It is based on relating, in a novel way, polymer-chain structure with random-walk structure in the context of Ornstein-Zernike equations. It incorporates much of the interaction-site description of correlation used in reference-system interaction site model (RISM) theory but introduces several simplifying approximations in connecting the RISM equation to random-walk theory that departs in a significant way from the extension of RISM used in polymer RISM (PRISM) theory. Both continuum-space and lattice-gas versions of the theory are summarized, and the extension of the theory to a self-consistent Ornstein-Zernike approach (SCOZA) for polymers is given.