In spring 2009, the Center on Education Policy (CEP) continued its research on the impact of test-based federal and state accountability policies by conducting case studies of six high schools in six different districts within Washington State. The purpose was to learn more about the curricular and instructional changes that administrators and teachers have made to raise student achievement and respond to the No Child Left Behind Act (NCLB) and related state accountability requirements. A part of this research examined the impact of the Washington Assessment of Student Learning (WASL), which is used as both the high school test for NCLB and the state high school exit exam. The schools studied used a variety of instructional practices and included a mix of urban, suburban, and rural schools with diverse demographics. This report takes an in-depth look at how classroom practices have been influenced by No Child Left Behind and related state policies in Washington. Drawn from classroom observations and interviews, the report sheds new light on how teachers, principals, and administrators have responded to the federal school accountability law.