The No Child Left Behind Act of 2001 (NCLB) was a U.S. Act of Congress that reauthorized the Elementary and Secondary Education Act; it included Title I provisions applying to disadvantaged students. It supported standards-based education reform based on the premise that setting high standards and establishing measurable goals could improve individual outcomes in education. The Act required states to develop assessments in basic skills. To receive federal school funding, states had to give these assessments to all students at select grade levels.

The act did not assert a national achievement standard—each state developed its own standards. NCLB expanded the federal role in public education through further emphasis on annual testing, annual academic progress, report cards, and teacher qualifications, as well as significant changes in funding. While the bill faced challenges from both Democrats and Republicans, it passed in both chambers of the legislature with significant bipartisan support.

By 2015, bipartisan criticism had increased so much that a bipartisan Congress stripped away the national features of No Child Left Behind. Its replacement, the Every Student Succeeds Act, turned the remnants over to the states.