Online review sites provide increasingly important sources of information in tourism product purchases. We tested experimentally how source, content style, and peripheral credibility cues in online postings influence four consumer beliefs, and how those in turn influence attitudes and purchase intentions for an eco-resort. We compared tourists' posts to managers' posts, containing vague versus specific content, and with or without peripheral certification logos. First, we tested effects of tourists' beliefs about utility, trustworthiness, quality and corporate social responsibility on attitude toward the resort and purchase intentions. Second, we tested the role of source, content, and certification on the beliefs. The interactions are complex, but broadly tourists treat specific information posted by customers as most useful and trustworthy. Their purchase intentions are influenced principally by their overall attitude toward the resort and their beliefs in its corporate social responsibility.