The current study examined the relation between autism severity at baseline, type of intervention employed and outcomes in young children with autism spectrum disorder (ASD). Seventy-eight children with ASD, aged 15-35 months (M=25.4, SD=4.2), received either applied behavioral analysis (ABA) or integration of several intervention approaches (Eclectic) in community center-based programs. Outcome was measured after 1 year of intervention using standardized autism diagnostic tests, and cognitive and adaptive skills evaluations. ASD diagnosis was highly stable (99%). Both intervention groups improved significantly in verbal cognitive abilities and in socialization and communication adaptive skills, but no significant difference between the intervention groups was documented. Less severe autism symptoms at baseline were associated with better progress in adaptive skills and in cognitive abilities. Within the group with less severe autism symptoms, those who received Eclectic intervention had a better outcome than those who received ABA in communication and socialization adaptive skills as reported by the parents, but not in the standardized cognitive test results. The child's baseline social abilities and deficits appear to be crucial variables for intervention outcomes and should be considered in treatment approach decision-making. (Contains 3 tables and 2 figures.)