Most introductory courses are held in large lecture halls, with students typically sitting in either the front, middle, or back of the classroom. In a mixed-methods study of student attendance, performance, and seat choice, we found that students who chose to sit behind their peers performed nearly a full grade level worse than their peers who sat in the middle and front of the classroom. They also attended class significantly less often than students in the front and middle of the room. Although students sitting in the back had worse performance in all five categories measured (attendance, unit exams, in-class work, final exam, and final course grade), these differences were eliminated by the mediating effect of attendance in all cases but those involving in-class work and unit exams. Students chose to sit where they did for diverse reasons. The results of this study demonstrate the relative importance of attendance and seat position on student performance in a large general biology course.