(Future) teachers should acquire skills in sourcing science-related information online, so they can use evidence appropriately in their pedagogical practice. To successfully use such evidence, it is vital that teachers critically question their selection of online information. Based on findings from collaborative learning, we hypothesized that collaboration promotes teachers' critical elaboration of their selection of online educational information. Additionally, collaboration allows for social comparison and may thus impact teachers' self-efficacy in seeking information. In a 2 × 2 mixed-design study with the between-participants factor reasoning (individual vs. collaborative) and the within-participants factor self-reported information seeking self-efficacy (pre vs. post the reasoning task), each of N = 83 future teachers individually sought online information regarding the educational use of mobile phones in classrooms. This constituted a realistic search on the Internet, in a natural setting. Based on each participant's particular search, s/he was asked to select the online sources that s/he perceived relevant for reasoning whether mobile phones should be used in class. To foster reflection on how they selected information, participants were asked either to reason individually (individual group, n = 33) or to chat collaboratively (collaboration group, n = 50 in 25 dyads) about their selections. Participants in both groups reported higher information seeking self-efficacy after the reasoning task. Yet participants who collaboratively reflected on their selections more frequently showed elaborated reasoning behavior, than did participants in the individual group. Nonetheless, participants in both groups referred to certain criteria that guided their selection (i.e., criteria related to the information, the provider of information, or media) with the same frequency. Considering the potential benefits and challenges of collaboration, we discuss the findings in terms of how to promote future teachers' ability to critically reflect on their selection of online educational information.