Although actual experiences of upward social mobility are historically low, many adolescents and adults express a "belief" in social mobility (e.g., that social status can change). Although a belief in upward mobility (e.g., that status can improve) can be helpful for economically disadvantaged adolescents and adults, a belief in upward social mobility in adults is also associated with greater acceptance of societal inequality. While this belief might have similar benefits or consequences in children, no previous work has examined whether children are even capable of reasoning about social mobility. This is surprising, given that elementary-aged children exhibit sophisticated reasoning about both social status, as well as about the fixedness or malleability of properties and group membership. Across an economically advantaged group of 5- to 12-year-old American children (N = 151, M[subscript age] = 8.91, 63% racial majority, 25% racially marginalized; M[subscript household income] = $133,064), we found evidence that children can reason about social mobility for their own families and for others. Similar to research in adults, children believe that others are more likely to experience upward than downward mobility. However, in contrast to adult's typical beliefs--but in line with economic realities--between 7- and 9-years-old, children become less likely to expect upward mobility for economically disadvantaged, versus advantaged, families. In sum, children are capable of reasoning about social mobility in nuanced ways; future work should explore the implications of these beliefs.