Accelerated light stability tests employ high-intensity illumination sources to speed the fading process and have been based on the assumption that light fading and light-induced staining reactions follow the reciprocity law; that is, for equivalent klux/hour light exposures, the amount of fading, changes in color balance, and development of d-min stain will be the same in accelerated light stability tests employing high-intensity illumination (e.g., 35 klux for 24 hours per day) as it is under low-level, ambient display conditions (e.g., 450 lux for 12 hours per day) as long as the temperature and relative humidity conditions are the same in both cases.In this ongoing, long-term study, reciprocity behavior is evaluated using high-intensity 35 klux illumination and lower-intensity 1.0 klux fluorescent illumination. Both test environments are maintained at 24°C and 60% RH. Dye-based and pigmented inks printed on various types of inkjet photo media are included, along with representative traditional color and black-and-white photographic prints made with RC (polyethylene resin-coated paper) supports.Potential problems in the design of reciprocity behavior tests for inkjet materials and interpretation of data from these tests are discussed.