Educators, policymakers, and parents have begun to focus more on children’s math learning in the earliest years. Yet parents and teachers still find it challenging to know which kinds of early math skills merit attention in the classroom. Determining how to help children achieve in math is important, particularly for children from low-income families who often enter school with weaker math knowledge than their peers. A new longitudinal study conducted in Tennessee has found that low-income children’s math knowledge in preschool was related to their later achievement—but not all types of math knowledge were related equally. The findings suggest that educators and school administrators may want to consider carefully which areas of math study they shift attention to as they develop curricula for the early years.