Multiple text comprehension can greatly benefit from paying attention to sources and from using this information for evaluating text information. Previous research based on texts from the domain of history suggests that source-related strategies are acquired as part of the discipline expertise as opposed to the spontaneous use of these strategies by students just entering a field. In the present study, we compared the performance of students and scientists in the domain of psychology with regard to (a) their knowledge of publication types, (b) relevant source characteristics, (c) their use of sources for evaluating the credibility of multiple texts, and (d) their ability to judge the plausibility of argumentative statements in psychological texts. Participants worked on a battery of newly developed computerised tests with a think-aloud instruction to uncover strategies that scientists and students used when reading a text. Results showed that scientists scored higher in all of the assessed abilities and that these abilities were positively correlated with each other. Importantly, the superior performance of scientists in evaluating the credibility of multiple texts was mediated by their use of source information. Implications are discussed in terms of discipline expertise.