This research examines the use of new music technologies as clinical interventions for individuals with autistic spectrum disorders. The technological application mediates and supports group music making. The intervention is designed to affect the domains where autistic individuals show symptomatic behaviors: communication, psychosocial interaction, and repetitive behavior. Furthermore, through working with the interface, a user generates quantifiable information pertaining to their cognitive performance on domain-specific cognitive tasks. This information is valuable for correlation with emergent social behavior as measured by the system. The primary contribution of the work will be to develop the design principles and methodology to track cognitive features over the course of a complex music interaction.