This study addresses an individual's performance, relating it to eyesight changes due to the aging of the individual and to color computer screens used for computer-based-instruction not designed specifically for older students. This study determines how existing research in gerontology, human-computer interface, and color use in visual graphics can be applied to the design of computer screen displays containing color text and backgrounds and how various color combinations will affect performance by adult learners forty years of age and older. The results of this research provide software developers and instructional designers guidelines to use when designing computer screen displays for use in instructional computing settings involving older adults.