The author measured the reliability of introductory biology students’ claims regarding lecture attendance, help session attendance, and reading assignment compliance. In all areas, students’ reported behaviors were different than their actual behaviors. Also, penalties for excessive absences did not substantially improve either attendance or academic performance. These data indicate that students’ self-reports of these course-related behaviors are unreliable and that penalties for absenteeism are ineffective for improving attendance and grades. Strategies for enhancing students’ success in introductory science classes are also discussed.