This study investigated families of children with autism spectrum disorders using early intervention and early childhood services, as well as the perceived efficacy and developmental outcomes related to the services and service delivery methods. Results indicated that a variety of recommended practices are not being used by families and interventionists and that intensity of engagement is less than suggested. Parents indicated that parent training was the most effective service in contributing to their child's growth. Significant, yet small, correlations were found between several intervention services/service delivery models and developmental outcomes across areas, including social, emotional, and cognitive development. The importance of assessing social validity related to outcomes is addressed, as are potential implications for service providers.