Prior models suggest that math attitudes and ability might strengthen each other over time in a reciprocal fashion (Ma, 1997). The current study investigated the relationship between math interest and skill both concurrently and over time in a preschool sample. Analyses of concurrent relationships indicated that high levels of interest were related to strong math skills. Even when controlling for initial interest and a brief intelligence measure, math skills predicted math interest approximately 5 months later; in the same way, early interest predicted later skill, even controlling for initial interest. These findings suggest that a reciprocal relationship between math interest and math ability may be in place as early as preschool. (Contains 4 tables and 1 footnote.)