Two experiments were conducted to assess an online version of Keller's personalized system of instruction, called computer-aided personalized system of instruction (CAPSI), as part of a blended learning design with regard to course knowledge and critical thinking development. In Experiment 1, two lecture sections of an introduction to University course received a CAPSI assignment while two received an extra paper assignment. In Experiment 2, one lecture section of an introduction to University course received a CAPSI assignment while another lecture section was assigned a research paper. In the two experiments the CAPSI sections consistently outperformed the sections with which they were compared, indicating that CAPSI is a viable option in higher education.