The problem presented by this study was reduced synchronous instruction in online learning environments often causes students to disengage by not participating in coursework or completing assignments. Additionally, a reduced amount of synchronous instruction opportunities yielded a reduction in coursework progress, decreased interaction, and reduction in successful course completion among online students specifically in 11th and 12th grade. The purpose of this quantitative correlational study was to determine the relationship between synchronous instruction and student engagement (participation and course completion), and synchronous instruction and course pass rates specifically for 11th and 12th grade online students in Nevada. This study focused on examining four courses (English, Math, Science, and History) associated with 11th and 12th grade online students and the correlation between the amount of synchronous instruction, to their overall engagement and overall course completion grades. Student data included student participation (course completion), synchronous instruction, and final course grades. This study was based on one online school, Nevada Connections Academy, serving students all across the state of Nevada. Throughout this study, a focus on synchronous instruction and its correlation to participation and course pass rates was investigated. Previous research consistently indicated/revealed synchronous instruction produces a positive impact on overall student learning (Claman, 2015; Garrett Dikkers, 2015). Overall, this study yielded results that showed some positive correlation between synchronous instruction and participation, course completion, and course pass rates, but did not show an overall significance. [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.]