This cross-sectional study assessed the relation between spatial skills and mathematics in 854 participants across kindergarten, third grade, and sixth grade. Specifically, the study probed for a threshold for spatial skills when performing mathematics, above which spatial scores and mathematics scores would be significantly less related. This study explored the relation of spatial and mathematics skills in three ways: age, type of spatial assessment, and whether the mathematics was new or already taught. Students were assessed on a battery of spatial and mathematical assessments. Spatial thresholds were discovered using a segmented regression analysis based on age and based on whether the mathematics was new or already taught, but not based on type of spatial assessment. Specifically, a spatial threshold was found in mathematics overall, in third and sixth grade students, in new and already taught mathematics for kindergarteners, in new mathematics for third graders, and in new mathematics for sixth graders. Thus, a spatial threshold was found in these instances: the relation between spatial and mathematics scores significantly decreased for students who had spatial scores above a threshold, relative to students below the spatial threshold. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]