Telling children that they can learn from their mistakes is common practice. Yet research indicates that many teachers in the United States limit public attention to errors during mathematics lessons (Bray 2011; Santagata 2005). Some believe that drawing attention to errors publicly may embarrass error makers or may be confusing to struggling learners. However, exploratory research suggests that focusing on errors can lead to increased student engagement among struggling learners (Bray 2007). In general, the strategy of publicly analyzing and discussing mathematical errors is thought to promote conceptual understanding (Borasi 1994; Kazemi and Stipek 2001). This article explores the potential of using errors to advance students' mathematical understanding and presents a framework for infusing a focus on errors into mathematics instruction. (Contains 4 figures and 1 table.)