The problem this qualitative case study addressed is how poor online teacher communication has resulted in students enrolled in full-time virtual schools underperforming academically with assignment completion. The purpose of this study was to explore teachers' perceptions of how their online communication strategies contribute to the timeliness of assignment completion by underperforming students in a Title I online high school (grades 9-12). This study was grounded by a theoretical framework based on Moore's transactional distance theory. The guiding research question of the study was how do high school teachers perceive their online communication strategies contributing to the timeliness of assignment completion by underperforming students in a Title I online high school. The study was accomplished by conducting semi-structured interviews with 10 teachers, as well as a focus group with five teachers, all within a Title I online high school in Southern California. The findings of this study demonstrated how teachers' online communication reduces transactional distance and contributes to the timeliness of assignment completion by underperforming students in a Title I online high school. Several themes were identified, including social and academic characteristics of teacher-student interactions and parent/guardian/learning coach involvement. Recommendations for future research include expanding the study to include student perspectives, replicating the study in a non-Title I online high school, and exploring the impact of schoolwide communication best practices. [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.]