The present study examined the effectiveness of two interventions, Imitation Responding (IR) and Intensive Behavior Treatment (IBT) used as initial treatment programs for autistic children enrolled in ordinary preschools. The interventions were carried out by parents and/or preschool teachers with supervision from Child Adolescent Habilitation and Health Clinics. Children were randomly assigned to either the IR group or the IBT group. The IR group received a new focused imitation treatment averaging 2.2 hours per week, while the children in the IBT group received 14.4 hours treatment per week. The outcome was measured with subscales from PEP-3 and Vineland-II, covering language and social domains. The between-group comparison revealed no significant differences in effect of treatment during the 5 months that encompassed the period from pre- to posttest. Within-group comparisons revealed significant changes on four subscales for the IR-group, with the highest effect sizes for play and expressive language, while for the children in the IBT-group a significant gain was evident for five subscales with the highest effect sizes observed for expressive and receptive language. These findings suggest that IR can be used as an initial and complementary method in settings where IBT is usually the primary treatment of choice.