Currently, there is a paucity of data on the efficacy, types and hours of intervention children with autism spectrum disorders (ASD) are receiving in real world settings. The goals of the current project were to (1) identify the hours of home and school interventions received by a sample of 237 children with ASD and (2) determine whether these hours of intervention predicted an increase in the level of adaptive functioning and a decrease in maladaptive functioning over the course of one year. To obtain independent measures of the students' adaptive and maladaptive functioning in the home and school, parents and teachers were asked to complete the Pervasive Developmental Disorder Behavior Inventory (PDDBI) on each child in the spring of two consecutive years. Analyses on the PDDBI replicated previous research indicating that the scales have excellent internal consistency, moderate to excellent inter-rater reliability, and good to excellent test-retest reliability. Overall, children with autism spectrum disorders, in our sample, made few treatment gains over the course of a single school year. While the National Research Council recommends children with autism receive 25 hours of specialized treatment, the children in our sample received just over 17 hours of specialized intervention, with an average of 13.66 school hours and 3.64 home hours. It was hypothesized that the total hours of school intervention would emerge as the most important predictor of functioning; however, this was not the case. Rather, pre-test scores seemed to predict the level of growth from Time 1 to Time 2. An increase in hours of intervention did not generally predict an improvement in adaptive or maladaptive skills; in some cases, more hours of intervention were associated with a decline in functioning. This finding may be partially accounted for by the fact that children with more severe autism tended to receive more hours of treatment intervention.