Proponents of the recent and widely adopted Common Core State Standards argue that high quality curricular standards are critical to students’ educational success. Little clear evidence exists, however, linking the quality of such standards to student achievement. I remedy this by connecting data on state-level student achievement from 1994-2011 with measures of the quality of states’ curricular standards as judged by two independent organizations at three different moments in time. I show that, within states, changes in the quality of standards have little impact on overall student achievement. Improved standards do, however, raise achievement of 8th graders in low-scoring states, particularly for low-scoring students. Given the known weaknesses of U.S. middle schools, this result suggests that standards may be beneficial in settings where pedagogy would otherwise be poor.