The treatment of errors in mathematics classrooms has gained attention in recent years, with many researchers suggesting that errors should be used as starting points for student inquiry into mathematics. In the study reported in this article, we examined how teachers used discourse around errors to generate inquiry by looking at the treatment of mistakes in U.S. and Chinese elementary mathematics lessons. To do so, we videotaped 44 lessons from Chinese and U.S. first-grade (n = 15), and fourth- and fifth-grade (n = 29) classrooms and also interviewed the teachers of the lessons. We separated the lessons by the topic taught (place value or fractions) and analyzed them for frequency of students' errors and the types of teachers' responses to these errors. Results indicated that U.S. and Chinese students made errors at similar frequencies. However, the teachers in the 2 countries responded to errors differently. In particular, the U.S. teachers made more statements about errors than the Chinese teachers, who instead asked more follow-up questions about errors. Relying on qualitative analysis of teacher interview and in-class statements about errors, we shed light on both how teachers used errors for inquiry and what teachers believed about errors. (Contains 1 table.)