Autism spectrum disorders (ASDs) are characterized by impairments in social skills, communication, and cognitive and behavioral functioning. Successful interventions for children with ASDs thus have the potential to not only affect outcomes of the child but may include substantial health benefits for the family. Guidelines for evaluating the cost-effectiveness of services recommend using the cost per quality adjusted life year (QALY) gained. To date, no studies have attempted to evaluate whether instruments to measure QALYS in children with ASDs are sensitive to the condition. In addition, research is needed to account for family effects in cost- effectiveness analysis. This research will address these issues by evaluating the sensitivity and psychometric properties of alternative generic instruments for measuring QALYS in children with ASDs and by determining whether caregiver QALYS should be incorporated into the cost-effectiveness model. Findings from the study will improve methods to accurately assess the cost-effectiveness of interventions to treat children with ASDs and assist in the translation of experimental findings into evidence-based policy for decision making.