This study examines test taking patterns of students enrolled in an introductory economics class who could complete their exams electronically at any time-of-day or day-of-week. Exam completion patterns are related to several student characteristics including gender, class rank, major, and whether the student was enrolled online. Statistical differences in both time-of-day and day-of-week were observed across these strata and related to overall performance. The majority of students completed their exams in late evening time periods, which negatively affected overall performance. These results have important implications for educators and may partially explain past anomalous results in other studies of student study habits.