In this article, the color appearance of a large (85 degrees) homogeneous self-luminous visual stimulus was studied in a psychophysical experiment. Large stimuli were displayed on a plasma display panal (PDP) monitor. The large stimuli were viewed with a fixed viewing time (2 s). They were compared with 2 degrees and 10 degrees stimuli presented on a grey background on a CRT monitor. The so-called "color size effect" was found to be significant. The color stimulus was perceived to be lighter when it was large compared with the 2 degrees and 10 degrees situation. But we did not find the general increase of chroma claimed in previous literature. We found only small hue changes. A model of the color appearance of large-field stimuli is presented in terms of the CIELAB L*, a*, and b* values of the corresponding 2 degrees and 10 degrees stimuli. (c) 2007 Wiley Periodicals, Inc.