Several Department of Defense (DoD) offices are responsible for estimating and monitoring the costs of defense systems and forces in support of planning, programming, budgeting, and acquisition decisions. For example, the Cost Analysis Improvement Group (CAIG) in the Office of the Secretary of Defense (OSD) provides independent cost estimates and reports on life-cycle costs of major defense acquisition programs (MDAPs) in Acquisition Category ID (see Reference ). Cost agencies and centers in the relevant defense components provide independent estimates for other MDAPs. The OSD CAIG leads efforts by these and other offices and organizations to improve the Defense Department's technical capabilities to forecast future costs. Near the beginning of each year, during the DoD Cost Analysis Symposium, the CAIG reviews the status of the Defense Department's capabilities to estimate the costs of defense systems. Several months later, representatives from offices that sponsor defense cost research meet at the Institute for Defense Analyses (IDA) at the Cost Research Workshop to exchange information on their ongoing and planned cost research projects and discuss current issues. The workshop, jointly sponsored by the OSD CAIG and IDA, has been held every year since 1989 (see References [2 through 21]). The 2008 IDA Cost Research Workshop, held on May 22, 2008, focused on issues related to Department of Defense contractor data reporting systems. Table 1 shows the participants in this year's workshop, and Table 2 presents the workshop agenda. This document summarizes the proceedings of the 2008 workshop (Chapter II) and catalogs defense cost research projects in progress or planned at the time of the workshop (Chapter III).