This report documents research findings from a RAND project titled "The Relative Cost Effectiveness of Military Advertising," the goal of which was to develop and apply a methodology for assessing the cost effectiveness of the services' advertising programs and to provide guidance for a more efficient allocation of resources in the future. The project was sponsored by the Director for Accession Policy (Force Management Policy). This report examines issues related to the effectiveness of recruiting advertising during the 1980s and 1990s. It describes the policy context, summarizes the current state of knowledge, and identifies several conceptual and methodological issues. In addition, it describes a framework developed for estimating advertising effects and how that framework was applied in an analysis of 198Os Army advertising programs. It also discusses how this methodology was used to analyze 1993-1997 DoD-wide information. The empirical results from the study strongly support the view that advertising has been a cost effective recruiting tool and provide some guidance for future improvements. Data deficiencies and analytic challenges associated with recruiting environment complexity, however, made it impossible to determine the most effective mix of advertising. Nonetheless, the concepts and methods developed can help guide future advertising research, and the general policy conclusions regarding past advertising programs remain valid. Additional research is necessary if future allocations of recruiting resources, including advertising dollars, are to be made optimally.