From 2008 through 2013, the DoD plans to invest over $16 billion to develop and procure additional unmanned aircraft systems. DoD recognizes that it must achieve greater commonality among the military services' unmanned aircraft programs. This report assessed the progress of selected unmanned aircraft acquisition programs, examined the extent to which the services are collaborating and identifying commonality among those programs, and identified key factors impacting the effectiveness their collaboration. It analyzed cost, schedule, and performance data for eight unmanned aircraft systems -- accounting for over 80% of DoD's total planned investment in unmanned aircraft systems from 2008 through 2013 -- and two payload programs.