Down Syndrome children exhibit language delays, particularly in expressive abilities, more severe than would be anticipated from their cognitive level alone. This research project sought to develop a procedure for introducing total communication into the home environment of prelinguistic Down Syndrome infants and for comparing the relative effectiveness of the oral and total communication approaches on an individual basis. A play-based language intervention was designed, using a single-subject simultaneous treatment design to evaluate a 14-month-old Down Syndrome child's progress in both speech and total communication modalities. Two equivalent 10-word sets were introduced during free play; with one set of 10 toys, manual signs augmented speech, while for the other 10 toys only speech was used. Results indicated that comprehension was not differentially affected by the type of communication approach used. However, the child was able to use manual signs expressively many months before any understandable words were used. His use of manual signs did not inhibit his use of speech. (Author/JDD)