Poly(p-phenylenevinylene) can be loosely viewed as a regular copolymer of polyacetylene and poly(p-phenylene). The electronic structure of polyacetylene, poly(p-phenylene), and poly(p-phenylenevinylene) have been studied using UV photoelectron spectroscopy and quantum chemical calculations based upon the valence effective Hamiltonian method. Excellent agreement between theory and experiment allows for a detailed description of the evolution of the electronic structure in this polymer series