The bulk of previous research on students' perceptions of open educational resources have lacked a control group of students rating traditional textbooks. Moreover, few studies have examined differences in the perceptions of online students and those taking classes in the classroom. A 2 × 2 cross-sectional design was used in which 925 students, assigned either a traditional textbook or an open textbook in either an online or classroom environment, were recruited to complete an online survey. Students assigned open textbooks were almost twice as likely to report using their textbooks, they used them more frequently, and for more time per week overall. Students assigned open textbooks also perceived a greater degree of overlap between the textbook, lecture, and quiz material than did students assigned traditional textbooks. Finally, ratings of the open textbooks were significantly higher than ratings of the traditional textbooks overall and on 11 of 15 different dimensions. Few differences in the online and classroom students were detected, suggesting both groups experienced similar benefits of the open textbooks. These findings demonstrate that replacing traditional textbooks with open textbooks may help to offset some of the financial hardships students face while improving students' engagement and satisfaction with their assigned textbook.