The present study investigated how undergraduates judged the trustworthiness of different information sources that they read about climate change. Results showed that participants (N = 128) judged information from textbook and official documents to be more trustworthy than information from newspapers and a commercial agent. Moreover, participants put most emphasis on content and least emphasis on date of publication when judging document trustworthiness. When judging the trustworthiness of the textbook, they emphasized criteria differently than when evaluating other types of documents. Results also indicated that readers low in topic knowledge were more likely to trust less trustworthy sources and failed to differentiate between relevant and irrelevant criteria when judging the trustworthiness of sources. (Contains 4 figures.)