Policymakers have long sought to raise expectations for students through standards-based reform. I examine the extent to which the Common Core State Content Standards (CC) affected student achievement and the size of achievement gaps. I merge together data on preparation for and implementation of the CC with the National Assessment of Educational Progress student-level data. To identify the effect of CC on student outcomes, I compare early implementors of the CC to late implementors of the CC in a difference-in-differences framework. I find the initial effect of the CC on math scores was positive. The CC had a large positive initial effect on economically advantaged students but no detectable initial effect on economically disadvantaged students. Raising state expectations without addressing the structural issues burdening economically disadvantaged students may result in unintended consequences.