The relative therapeutic effectiveness of a large, long established state institution offering primarily custodial care; a large, modern state institution offering a therapeutic program of planning activities; and a small, psychoanalyti-cally oriented day-care unit emphasizing the emotional relation between staff and children, was evaluated in terms of behavioral change over a year''s time. The 3rd setting was the most effective in bringing about improvement in the areas of Relationship, Mastery, and Psychosexual Development; but none of the milieus produced changes in Communication and Vocalization. The milieu in which therapeutic activities were planned with care but executed with indifference was as ineffective as the milieu offering custodial care. It seems that therapeutic change is slow in autistic children for 2 reasons: not only does progress within each area proceed by exceedingly fine steps, but progress also seems to be area-specific rather than generalizing to other aspects of the children''s lives.