The success of standards-based education systems depends on 2 elements: strong standards, and assessments that measure what the standards expect. States that have or adopt test-based accountability programs claim that their tests are aligned to their standards. But there has been up to now no independent methodology for checking alignment. This article describes and illustrates such a methodology and reports results on a sample of state tests. In general, although individual items align quite well with some standard, the tests as a whole are not well aligned. With few exceptions, the collections of items that make up the tests that we examined do not do a good job of assessing the full range of standards and objectives that states have laid out for their students. This misalignment can have serious consequences for instruction and for the validity of test results.