The expressive and receptive use of three written words was taught to three mute autistic adolescents using a procedure based on Terrace's errorless discrimination model and Premack's language training with chimps. Expressive language was measured by the subject's selection of the appropriate word card from among the available alternatives when the corresponding object was presented. Receptive language was measured by the subject's selection of the appropriate object from among the available alternatives when the corresponding word card was presented. The sequence of the presentations and the order of placement of the available alternatives were randomized. The three subjects required 979, 1,791, and 1,644 trails, respectively, to master both the expressive and receptive use of the three words. The correct response rates for the three subjects over the entire training program were 92, 92, and 90%, respectively. It was concluded that, as concrete visual symbols, written words may provide a viable communication system for the mute autistic. The implications for treatment are discussed and suggestions for future research are made.