PDFThe Smalltalk-80 user interface and graphics model are based on monochromatic graphics. One natural step in the evolution of the Smalltalk-80 system is the addition of color. This paper describes an implementation of color Smalltalk. Classes have been defined to manipulate visual color models and colored graphics objects. The extensive collaboration between classes which describe color, classes which perform basic graphics operations, and classes in the user interface is explored. Issues in the design and implementation are examined. Potential future directions for object-oriented color systems are discussed.