To effectively address the issue of youth alcohol use, communities need to have sufficient infrastructure and capacity in place to operate effective prevention programs. This study evaluates community capacity in the state of Hawai'i, using the Capacity Assessment Survey administered to stakeholders in the youth alcohol prevention system. Capacity is quantified with gap scores, which measure the discrepancy between an agency's performance of an attribute and the attribute's relative importance. Six assessment areas, termed capacity domains, are defined. Results are given for each county and the state overall. Based on these results, communities need to prioritize capacity-building efforts specifically in the domains of effectiveness, funding/resource availability, and sustainability. Organization, workforce skills/knowledge, and cultural competency were categorized as relative strengths in comparison, but gap scores are nevertheless significantly greater than 0 ("ideal"; p < .001), indicating these areas need improvement as well. Suggestions for improvement in each capacity domain are given. This assessment is the first step in a five-step planning process to implement youth alcohol prevention programs in communities in Hawai'i.