Both anecdotal and systematic evidence points to the importance of teachers for students' long-run success. Previous research on effective teachers has focused almost exclusively on student test score gains in math and reading. For this study we are able to link middle and high school teachers to the class-attendance of students in their classrooms, and to create measures of teachers' contributions to student attendance. Student absence is a growing concern for policy makers. On average, secondary students in the United States are absent from school three weeks per year (Snyder & Dillow, 2013), and even when they are in school, they miss many classes. We find systematic variation in teacher effectiveness at reducing class absences. These differences across teachers are as stable as those for student achievement. While positively correlated with teachers' value-added to achievement, teachers' value-added to attendance is clearly different and contributes independently and approximately equally to long run student outcomes including high school graduation.