Language is a powerful cognitive tool. For example, labelingobjects or features of problems can support categorization andrelational thinking. Less is known about their role in makinginferences about the structure of mathematics problems. Wetest the impact of labeling decimals such as 0.25 using formalplace value labels (“two tenths and five hundredths”)compared to informal labels (“point two five”) or no labels onchildren’s problem-solving performance. Third- and fourth-graders (N = 104) were randomly assigned to one of threeconditions (formal labels, informal labels, or no labels) andlabeled decimals while playing a magnitude comparison gameand number line estimation task. Formal labels facilitatedperformance on comparison problems that requiredunderstanding the role of zero, which highlighted place valuestructure. However, formal labels hindered performance whenexplicit understanding of place value magnitudes wasrequired. Findings highlight how the language teachers andstudents use can impact problem-solving success.