Gel permeation chromatography (GPC) is one of the most important characterization tools of the polymer chemist. The coupling of GPC with ultraviolet (UV) spectroscopy (GPC-UV) increases the power of the tool even further. This paper describes the use of GPC-UV to determine the location and amount of functional groups and chromophores in polymers. This information is important for characterization of polymers being used as building blocks for making block and graft copolymers, and for the elucidation of discoloration and polymer degradation mechanisms.