Abstract : This report identifies the primary causes of major cost growth through case studies of eleven Major Defense Acquisition Programs (MDAPs) and offers recommendations for better controlling cost growth in future programs. It identifies, with the full benefit of hindsight, particular decisions and mistakes that resulted in cost growth, not with the intent of blaming individuals, but to illuminate problems in the Department of Defense (DoD) acquisition process that point the way to the recommendations for improvements. In this context it is important that the reader bear in mind that successful Defense acquisitions depend on the efforts of many participants in the process. The Defense Acquisition Executive (DAE), to be sure, has primary responsibility for the key decisions on the major programs and for the overall functioning of the acquisition system, but the quality and successful implementation of these decisions depend on many others?the supporting staffs in the Office of the Secretary of Defense (OSD), the Joint Staff, the Services, including the Service Acquisition Executives (SAEs), government program managers and contracting officials, and the defense contractors. This large ensemble of participants must work well together as a team to provide the information and analyses to support good decisions and to carry them out once they are made. Decisions about MDAPs, moreover, touch on the core interests of important powers outside the formal acquisition process both inside and outside DoD, and the DAE must exercise a keen understanding of those forces, including the transcendental goals of the administration of which he is a key member. This report is intended, not to indict the past, but to help future decision-makers avoid the pitfalls it identifies.