This mixed methods study aims to describe and explain the effects of co-regulation on students' self-regulation, which is hypothesized to lead to better learning. Students (N = 42) in six online undergraduate and graduate courses worked in dyads for six weeks on shared activities. Variables of interest included students' self-regulated learning, co-regulated learning, and students' perceptions of the online course delivery based on a Community of Inquiry framework. Six students were also interviewed about their experiences in the dyads. A mediation analysis was conducted to detect if co-regulation mediated the relationship between students' self-regulation before and after working in dyads. A second mediation analysis was proposed to explore if post-OSLQ mediated the relationship between CRL and dyads' project grades. The results indicated that students' self-regulation prior to that dyad activity was not a significant predictor of students' co-regulated learning. However, co-regulated learning was a significant predictor of student self-regulation after dyads activity. Results indicated that students' self-regulation after dyad activities was a significant predictor of the online course delivery. Results of mediation analysis did not support the mediating role of co-regulation between students' self-regulation prior and after the shared activities and the second mediation analysis could not be conducted due to little variability in dyads' project grades. Analyses of the interview data suggest that dyads co-regulation experience was impacted by instructional factors, technical factors, environmental factors and students' social factors. Implications for instruction and future research are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]