First of three articles by Faber Birren on color theory for textile designers. It argues that woven threads of different colors blend visually in the eye rather than chemically as dyes do, so yellow and blue threads give gray, not green. It compares three color systems (the physicist's light triad, the pigment triad and the visual tetrad) with five diagrams, and uses a black-and-white figure to show how diffusion reduces contrast. It ends with a summary: isolated large areas can use opposing colors for force, while closely woven threads work best in analogous colors.