The purpose of this study was to examine how. sex, gender schema, and gender-related spatial activities affect performance on a mental rotation task. Undergraduate students (53 men and 122 women) completed the Mental Rotations Test, the Bem Sex Role Inventory, and a demographics survey. Some students (17 men and 25 women) also completed the short version of the Spatial Activity Questionnaire. The hypothesis that men would perform in significantly better on the Mental Rotations Test than women was supported. Men, classified both as Aschematic and Schematic, performed significantly Letter on the Mental Rotations Test than women classified as Schematic and Aschematic. Gender schema, however, did not have a significant effect on performance on the mental rotation task within each sex. The hypothesis that persons participating in Masculine space-related activities would perform Letter in the Mental Rotations Test than persons participating in Feminine or Neutral space-related activities was not supported primarily because none of the participants scored as participating in Feminine activities, Such results suggest the need for further research to assess what effects, if any, participation in gender-stereotyped activities has on performance of the mental rotation task.