This literature review asserts that although findings indicate that children from a wide array of cultures and circumstances acquire similar mathematical understandings with little formal instruction, there is also substantial evidence that mathematical knowledge varies across social classes and cultural groups. The paper explores the literature devoted to explaining cultural differences in children's mathematics knowledge, including: (1) cultural variations in young children's mathematical activities (for example, Brazilian street children's competence with currency but not written numbers); and (2) linguistic variations in number systems. Educational implications are also considered. The paper concludes by noting that from the perspective of culturally-relevant instruction, racial and ethnic group differences in young children's mathematics knowledge reflect variation in the opportunities children have to engage in mathematical activities, rather than reflecting children's inherent ability. Teachers will need to move beyond a view of mathematics as a decontextualized and sequenced set of skills, and toward asking questions about, and giving value to how children use mathematics in their everyday lives. (Contains 47 references.) (EV)