The successful development of high-performance polymer optical waveguides depends critically on the stability of the materials during device fabrication. Typically, ensuring the stability of the organic chromophores contained in these materials represents the most difficult challenge. We present an overview of the mainly spectrophotometric techniques recently developed in our laboratory that have served as exceptionally useful tools in materials development. In addition, recent results involving the relative stability of various chromophores under exposure to simulated processing conditions are described. These allow for an improved understanding of the effects of variables such as temperature, oxygen concentration, and radiation intensity during fabrication on the performance of polymer optical waveguides.