The present study aims to explore the relationship between perceived message source (spokesperson) credibility and message compliance in response to a health risk message. Based on an experiment in Ireland (n = 406) and Belgium (n = 410), we test how the relationship between source credibility and message compliance is mediated by perceived threat and efficacy of the message, and moderated by power distance and uncertainty avoidance. A source that is perceived as more credible is found to increase message compliance by increasing both the perceived message threat and efficacy. The indirect effect of source credibility on message compliance through perceived efficacy is stronger for individuals with lower power distance and higher uncertainty avoidance.