The task of determining which of many available color-difference formulae is appropriate for any give application can be arduous. Researchers and practitioners alike are faced with the selection of one formula which best describes perceived color differences under conditions in which the equation is to be employed. The idea that one equation can be formulated which takes into consideration all factors affecting perceived color difference has yet to be realized, and perhaps never will. As a result, an “every man for himself” approach has developed. Yet, color-difference equations are continually being applied to conditions without empirical evidence to support their use. While the 1976 CIELAB Color Difference Equation has been applied for some time in the photographic industry, its use in describing the perceived magnitude of large color differences in photographic prints has not been validated. Furthermore, a good deal of research has suggested that the CIELAB equation is not applicable under numerous conditions of color-difference assessment. Nonetheless, the results of the study reported here support the use of CIELAB over four other formulae (CIELUV, CMC (1:1), Richter, and Yu’v’) for describing perceived color differences in photographic prints. CIELAB produced moderate correlations for both experienced and non-experienced color judges over the range of color space examined. The results of this work support the use of the 1976 CIELAB Color Difference Equation for describing the perceived magnitude of moderate and large color differences in photographic prints. / Master of Science