Since Berlin and Kay's proposal in 1969 of two universals concerning the meanings of basic color words, three kinds of information have become available to help in understanding the encoding sequence, that is, the temporal order in which the basic color categories are accorded lexical status. McDaniel (1972, 1974, forthcoming) demonstrates that the encoding sequence is best understood not as the successive encoding of foci, but as the successive differentiation of color categories. Field studies of the color systems of a Jivaroan, a Mayan, a Papuan, an Eskimo and three Austronesian languages have been critical in understanding the encoding sequence. Fuzzy set theory as developed by Zadeh (1965, 1971) provides a formalism for expressing the understanding of basic color categories. The present study brings together work by McDaniel, the field studies, and fuzzy set formalism. If a color category is viewed as a fuzzy set, vacillation between focus and boundary is avoided when discussing universal color categories, their interrelations, and the sequence in which they are encoded in evolving color lexicons. (CLK)