The purpose of this study was to determine whether there is a difference in spatial visualization ability between college students in STEM (science, technology, engineering, and mathematics) fields and those in non-STEM fields. The study also examined whether such a difference can be identified across gender. The study included over 850 male and female college students in a variety of disciplines. The mental rotation of simple and compound objects was used as an indicator of the spatial visualization ability. Participants in the study were anonymously surveyed for information about their major and their gender at the time of taking the mental rotation tests. The results of the study indicated that students majoring in STEM fields have significantly better spatial visualization abilities than those in non-STEM fields regardless of gender. According to the chi-square test used to evaluate the significance of the results, the difference in the average score between those in STEM fields and those in non-STEM fields was too great to be attributed to mere chance for both male and female students.