This work reports the effect of a revised attendance policy on attendance and course outcomes for two populations of students: introductory general chemistry students and upper-level chemistry majors. Initially, the attendance policy highlighted students' responsibility for the material covered in class. This was changed to a policy with a specified reduction in the course average for excessive absences. Attendance and final exam scores were tabulated for each group. Implementation of the new policy increased attendance and final exam scores for introductory students, but it had no effect on attendance and final exam scores for upper-level majors. This result suggests that introductory students would benefit from course policies with specific expectations for attendance.