Mathematical competence in middle childhood predicts socioeconomic status in adulthood. Therefore, it is important to understand the components that constitute mathematical competence from kindergarten to sixth grade. Using an analytical approach, in this article, I identify three components: understanding numbers, understanding mathematical symbols and their relevant principles, and converting problems into mathematical expressions. Evidence suggests that all three components significantly predict children's mathematical competence. However, the interrelations of the three components, as well as their unique contributions to overall mathematical competence, remain largely unexaed, with most studies focusing on only one of the three components. Exploring such issues can give researchers and educators a more comprehensive view of mathematical competence in childhood, and can lead to reconsiderations of important theoretical issues. The three-component framework of mathematical competence may also give educators insights on how to improve the mathematical competence of future generations.