The controversial No Child Left Behind Act (NCLB) brought test-based school accountability to scale across the United States. This study draws together results from multiple data sources to identify how the new accountability systems developed in response to NCLB have influenced student achievement, school-district finances, and measures of school and teacher practices. Our results indicate that NCLB brought about targeted gains in the mathematics achievement of younger students, particularly those from disadvantaged backgrounds. However, we find no evidence that NCLB improved student achievement in reading. School-district expenditure increased significantly in response to NCLB, and these increases were not matched by federal revenue. Our results suggest that NCLB led to increases in teacher compensation and the online gokkasten share of teachers with graduate degrees. We find evidence that NCLB shifted the allocation of instructional time toward math and reading, the subjects targeted by the new accountability systems.