Abstract Near infrared (NIR) spectroscopy was used to develop predictive models of color development for PVC film formulations subjected to accelerated weathering. The high correlations between color and NIR spectra result from the common polyene sequences origin of both measurements. The methodology should be applicable to transparent and filled systems. It provides a probe for investigating polyene sequence formation with minimal saturation effect limitations. The NIR technique can provide a complementary approach to mid‐IR and Raman studies of polymer photodegradation. J. VINYL. ADDIT. TECHNOL., 11:39–46, 2005. © 2005 Society of Plastics Engineers