We propose that standardized achievement test scores and report card grades differentially reflect student competencies determined by intelligence and self-control, two distinct traits shown to predict successful functioning in—and beyond—the classroom. Our model, described in more detail below, is graphically summarized in Figure 1. The present investigation tests predictions of this model in two independent samples of children followed longitudinally during their middle school years and in a third study in which middle school teachers were asked to compare the content and purpose of standardized achievement tests with report card grades.