Twenty-one subjects rated a random sequence of 144 color pairs on a categorical scale ranging from 1 (harmonizing) to 7 (clashing). Another group of 35 subjects rated each individual color on a set of semantic differential scales. The colors were also scaled objectively in terms of Munsell measures for hue, chroma, and value. The color harmony ratings were analyzed by using multidimensional scaling and invoking a weighted individual-differences Euclidean distance model. A two-dimensional solution accounted for 83.1 % ofthe variability in the transformed data matrices. On the basis of supplementary regression analyses, it was found that hue, value (brightness), and the psychological attribute "pleasantness," were the factors that influenced the color harmony judgments. In general, harmonious color combinations involved colors that were similar with regard to these attributes.Color harmony , the "suitability" of juxtaposed colors, is a complex phenomenon that is influenced by the individual colors' characteristics (i. e., hue, brightness, saturation) and their relative areas _ The most extensive study of this phenomenon was conducted by Helson and Lansford (1970), whose subjects rated the pleasantness of 125 colors on 25 colored backgrounds in five sources of illumination_ The principle factor determining the pleasantness of color combinations was brightness contrast -the most pleasant combinations involved large brightness differences between color and background, whereas the least pleasant combinations involved little or no difference.Hue and saturation contrast were less decisive factors . In the case of saturation, large differences between color and background tended to be judged as being more pleasant than were small differences; however, small differences in saturation could be judged as being pleasant or unpleasant, depending on whether or not there was a high degree of brightness contrast. The findings regarding hue differences were even more equivocal. Earlier studies had shown that the more pleasant combinations involved either zero, small, or large hue differences between color and background, but not intermediate. Helson and Lansford (1970) found that this generalization held for some hue families, but not for others.Helson and Lansford 's (1970) overall conclusion was that color harmony is not easily predicted and depends on the interaction of the spectral characteristics of illumination source, background color, and the hue, brightness, and saturation of the object color.