Modern colorant mixture theories and computer programs coupled with sophisticated spectrophotometric measurement techniques can be used to follow the rate of change in theconcentration of a colorant during the fading process. This study of the kinetics of the fading of the widely used artists' pigment, alizarin, incorporated many of the variables of importance inherent in various types of paint films and paint formulations. A few of the principal experi mental results are reported in this paper, the main emphasis being the validity of the first-order behavior to account for the pigment fading process.