This paper explores teachers' feedback practices in an online language teaching course. We examine several variables that could have an impact on providing effective and meaningful feedback essential to account for students' rate of completion of a one-semester course. Classroom size, amount of teacher-student and student-student interactions, and teachers' experience levels are considered when examining 43 upper-intermediate online English classrooms. These practices were checked against students' completion rates over the semester to identify the variables that may account for student progress. The data analysis helped assess the effect of a small teacher professional development intervention and indicates that student engagement is crucial in online language learning. [For the complete volume, see ED578177.]