With the development of the Internet as a main source of information, teenagers are increasingly faced with multiple documents which may contain contradictory statements, and whose reliability must be assessed. One way to assess information reliability is to evaluate the source of the information (e.g., author expertise, intention). However, teenagers rarely engage in such a sourcing process. The present study aims to explore the role of a potential explanatory factor of teenagers’ sourcing abilities: Advanced Theory of Mind (AToM). We hypothesized that AToM would be significantly related to teenagers’ evaluation skills when reading multiple documents, and in particular to their attribution of sources’ intentions and benevolence. We also hypothesized that this contribution will occur over and above teenagers’ word reading and textual inferencing skills. Seventy-two students in Grade 8 read a set of online documents about a fictitious socio-scientific controversy and answered comprehension and evaluation questions. AToM was a significant predictor of comprehension and evaluation performance. The role of AToM was especially important for the source’s evaluation and intentions questions. This study thus contributes to a better understanding of the possible factors of teenagers’ developing sourcing skills.