Project Summary With the release of Pre-Exposure Prophylaxis (PrEP) clinical guidelines by the CDC, there has been increased effort to identify effective strategies for increasing awareness, acceptability, and uptake of PrEP as a HIV primary prevention tool, especially among men who have sex with men (MSM). Conventional approach to developing HIV campaigns, such as social marketing, is fundamentally a ?top-down? approach by designing programs created by select individuals from a key population. In addition, most pre-testing of campaign messages is done using self-report methods, such as focus groups or likeability measures. Although these methods are useful, research has found that self-report effectiveness measures cannot reliably predict the effectiveness of campaign materials. Evidence from neuroscience has demonstrated that neural responses hold the potential to be significantly more reliable than self-report measures in assessing message effectiveness that is highly predictive of future behavior change. This proposal will examine the feasibility, acceptability, and utility of open contest approach and neuroimaging technique to develop and evaluate PrEP promotion messages for high-risk MSM in Baltimore, MD. Our multi-disciplinary research team brings together HIV prevention, open contest, and neuroimaging experiment experience; a long term history of working with MSM in Baltimore; and a rich local infrastructure for HIV research. The specific aims are: 1) Explore the feasibility and acceptability of open contest approach to soliciting PrEP promotion messages, and 2) Evaluate the effectiveness of PrEP promotion messages developed via open contest by assessing neural bases of persuasion. Findings of this proposed study will transform the design, evaluation, and implementation of HIV campaigns, potentially bringing new ideas for local health departments and community-based organizations in developing more impactful PrEP campaigns.