We study the causal effect of school curricula on students' stated beliefs and attitudes. We exploit a major textbook reform in China that was rolled out between 2004 and 2010 with the explicit intention of shaping youths' ideology. To measure its effect, we present evidence from a novel survey we conducted among 2000 students at Peking University. The sharp, staggered introduction of the new curriculum across provinces allows us to identify the effects of the new educational content in a generalized difference in differences framework. We examine government documents articulating desired consequences of the reform, and identify changes in textbook content and college entrance exams that reflect the government's aims. These changes were often effective: study under the new curriculum is robustly associated with changed views on political participation and democracy in China, increased trust in government officials, and a more skeptical view of free markets.