The purpose of this study was to examine gender differences across three types of spatial ability; namely, spatial perception, spatial visualization, and mental rotation in conjunction with working memory. The study utilized a causal-comparative research design involving group comparisons. In this design researchers collect data about variables that they have conceptualized to be in a causal relationship to each other, but there is no intervention as in experimental research. Participants in this study included approximately 200 students in second through eighth grades at one public school and one public charter school, all located in the same school district/county. Spatial ability was measured by four categories of spatial relations tests based upon spatial cognition research proposing that spatial cognition is comprised of "three separable dimensions": the Mental Folding Test for Children (spatial visualization), an adaptation of the Differential Aptitude Test: Space Relations (DAT: SR), Mental Rotation for Children, an adaptation of the Mental Rotations Test (MRT), Manikin Test (spatial orientation and transformation), and Mr. Peanut Test (visuo-spatial working memory). The resultant scores were used as measures of mathematical achievement and cognitive ability. Data were analyzed using MANOVA and ANOVA statistical analysis. Results suggested that mostly non-significant differences exist for spatial visualization abilities between males and females. The sole example of a significant difference between male and females was noted on the Mr. Peanut test in the fourth and fifth grades, accompanied with a partial Eta Squared (eta[superscript 2]) of 0.10. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]