Purpose: Calculus is generally offered as a freshman-year course and is a prerequisite for some advanced STEM-related courses in some undergraduate programs. However, some students experience difficulties in Calculus courses, leading to lower levels of achievement. Thus, there is a need to examine the factors which may be related to students' achievement in Calculus courses. According to relevant literature, procrastination can diminish students' achievement. Additionally, flow emerges as an important factor that may be related to students' achievement and procrastination, but these relationships have not been studied in the context of Calculus courses.