Active and collaborative learning has shown considerable promise for improving student outcomes and reducing group disparities. As one common form of collaborative learning, pair programming is an adapted work practice implemented widely in higher education computing programs. In the classroom setting, it typically involves two computer science students working together on the same programming assignment. The present study examined a cluster-randomized trial of 1,198 undergraduates in 96 lab sections. Overall, pair programming had no significant effect on students' course performance; subject matter interest; plans for future coursework; or their confidence, comfort, and anxiety with computer science. These findings were consistent across various student characteristics, except that students with favorable pretest scores exhibited negative effects from pair programming.