AT THE EAST BAY ACTIVITY CENTER IN BERKELEY, CALIFORNIA, TREATMENT INVOLVED THE MIXING OF AUTISTIC CHILDREN WITH LESS SEVERELY DISTURBED CHILDREN. NON-AUTISTIC CHILDREN IN THE GROUP WERE EXPECTED TO ACT AS CATALYSTS BY TRYING TO FORM SOME TYPE OF SOCIALLY MATURE RELATIONSHIP WITH THE AUTISTIC CHILDREN WHILE THE THERAPIST ENCOURAGED INTERACTION. HYPOTHESIS ONE STATED THAT TREATMENT EMPLOYED AT THE CENTER AND PARTICULARLY IN THE PLAY ACTIVITY GROUP SHOULD AID THE CHILDREN, BOTH AUTISTIC AND NON-AUTISTIC, IN DEVELOPING MORE SOCIALLY MATURE TYPES OF INTERACTION. BEHAVIOR RATINGS OF THE CHILDREN WERE MADE BY OBSERVERS. THE WILCOXEN SIGNED RANKS TEST SHOWED NO SIGNIFICANT IMPROVEMENT FOR THE GROUP DURING EITHER YEAR OF THE PROGRAM. MEASUREMENT OF INDIVIDUAL CHILDREN'S CHANGES BY MEANS OF T TESTS SHOWED THAT OF SIX CHILDREN IN THE FIRST YEAR'S GROUP, TWO SHOWED SIGNIFICANT CHANGES IN LEVELS OF INTERACTION (AT .005 AND .001 LEVELS). DURING THE SECOND YEAR, OF EIGHT CHILDREN, TWO SHOWED SIGNIFICANT CHANGES IN LEVELS OF INTERACTION (AT .01 AND .001 LEVELS). NONE OF THOSE CHILDREN WERE CLASSIFIED AS AUTISTIC. COMPARISONS OF MONTHLY MEAN FLUCTUATIONS OF THE AUTISTIC CHILDREN WITH THE CATALYSTS BY MEANS OF T TESTS WERE NOT SIGNIFICANT. HYPOTHESIS TWO STATED THAT THE TREATMENT PROGRAM SHOULD RESULT IN THE NONSOCIAL AUTISTIC CHILDREN'S GRADUALLY DIMINISHING THEIR AMOUNT OF DEPENDENT INTERACTIONS WITH THE THERAPIST AND BEGINNING TO INTERACT WITH OTHER CHILDREN IN THE GROUP. THE WILCOXEN SIGNED RANKS TESTS REVEALED NO SIGNIFICANT DIFFERENCES FOR EITHER YEAR IN PROPORTION OF INTERACTION WITH OTHER MEMBERS OF THE GROUP BETWEEN THE BEGINNING AND THE END OF THE YEAR. THE BIBLIOGRAPHY LISTS 12 ITEMS. DESCRIPTIVE ACCOUNTS OF THE THERAPEUTIC METHODS USED, ANECDOTAL RECORDS OF THE CHILDREN INVOLVED, THE RESULTS OF A FOLLOW-UP STUDY, A DISCUSSION OF THE NATURE OF AUTISM, AND A BRIEF SUMMARY OF THE PHILOSOPHY OF GROUP THERAPY ARE INCLUDED. THIS DOCUMENT IS AVAILABLE FROM PRENTICE-HALL, INC., ENGLEWOOD CLIFFS, NEW JERSEY. (TM)