Although spatial ability is related to success in the sciences, relatively little research has considered the relationship of spatial abilities with common misconceptions and broader conceptual difficulties in the Earth sciences. Spatial thinking and abilities have not commonly been directly addressed in traditional education. In this study, I found moderately significant positive correlations between scores on the ESC, a new test of Earth science conceptual understanding, and scores on each of three types, or factors, of spatial ability in university undergraduate non-science majors. Types of spatial ability tested included mental rotation, spatial perception, and spatial visualization. I found mental rotation to be the best predictor of ESC scores of the variables tested. Results suggest that an opportunity may exist to improve Earth science conceptual understanding by focusing on spatial abilities or the spatial aspects of concepts.