Although K-12 online learning has experienced exceptional growth, research in the area has lagged behind. This dissertation addressed this gap in the literature using a multiple article dissertation format. The first article used survey data from two online English courses at the Open High School of Utah (OHSU) to examine students' reported interactions with content, peers, and instructors. The large majority of students viewed all investigated types of interaction as educational and motivational. Students perceived learner-instructor and learner-content interactions to have significantly higher educational value than learner-learner interactions, and viewed learner-instructor interaction to be significantly more motivational than learner-content interaction. Furthermore, nine significant correlations were found between the time students spent on human interaction and course outcomes. The second article examined learner-parent and parent-instructor interactions within the same context. Similar to the first article, survey data was used to measure parents' and students' perceived quantity and quality of parental interactions with students and teachers. It was found that generally students and parents viewed parent-instructor and learner-parent interactions as motivational. Students viewed learner-parent interaction as significantly more motivational than did their parents. The quantity of reported parental interactions tended to negatively correlate with course outcomes. These negative correlations may be the result of parents' tendency to increase interaction levels following poor student performance and may not reflect the actual impact of parental interactions on individual student learning. When discussing the results in the second article, the claim was made that future research should look beyond the quantity of interactions and develop a theoretical framework that identifies and categorizes the roles of individuals in improving student outcomes. The third article of this dissertation presents such a framework that can help guide K-12 online research and design. The Adolescent Community of Engagement (ACE) framework consists of four main constructs that make up a K-12 online learning community. The first three "(student engagement," "teacher engagement," and "peer engagement") build on previously established online frameworks that originally emerged from higher education contexts. In addition, the ACE framework recognizes the role of parents in their child's learning and introduces a fourth construct, parent engagement, which builds on two previously established face-to-face frameworks. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]