In today’s politically polarized environment, college students need strategies to discern trustworthy information. Educational interventions have had modest success in teaching students to fact-check online information using lateral reading, i.e., leaving the original content to investigate information sources and claims. College students (N = 157, M = 20.2 years (SD = 4.0), 61.8% F) completed a semester-long online curriculum teaching fact-checking via lateral reading. Students made gains in their lateral reading attitudes (i.e., preference for fact-checking using lateral reading strategies) and use of lateral reading. Preference predicted use at posttest, but not at pretest. At posttest, preference also partially mediated the effect of reading comprehension on use. The majority of students mentioned cognitive and/or contextual factors when explaining how the Internet contributes to political polarization, though their awareness of such factors did not increase post-intervention.