The purpose of this study was to assess the impact of young students' prior attitude on source consideration when watching videos on controversial topics. Two hundred seventy-one seventh graders watched a series of videos in which two interviewees (one expert in the field, one layperson) expressed divergent positions on a socioscientific issue ("Will organic farming be able to feed the entire world population by 2050?"). After watching the videos, students were asked to recall the identity and arguments of the interviewees and indicate how far they had perceived them to be credible and convincing. If no effect of students' prior attitude was found on source recall, students were prompt to judge the interviewee who provided arguments that were congruent with their prior attitude as more credible and convincing that the interviewee that provided incongruent arguments. These results suggest that young students' beliefs contribute to their assessment of the credibility of an information source when watching videos.