The first part of this study examined class attendance of 959 students in 17 sections of undergraduate psychology classes. It was found that class attendance decreased from the beginning to the end of the semester. An investigation of 117 of the students found that attendance displayed moderate correlations with course grades. Students missed class most frequently because of the time needed to complete other course work, because the class was boring, because of illness, and because classes interfered with students' social life. Self-efficacy theory is proposed as an approach to explain attendance behavior. Includes eight references. (JDD)