The average educational attainment of US students is weak by international comparison. For example, mean results of PISA test scores are below the OECD [Organisation for Economic Co-operation and Development] average. This is despite substantial resources devoted to the schooling system. One partial explanation for this is that academic standards, curriculum and examinations are not sufficiently challenging in most US states. In 2001, Congress enacted the No Child Left Behind Act (NCLB) to raise achievement levels, especially of certain groups that perform badly. The Act requires states to establish clear content standards as to what students should know, to regularly assess performance and to set thresholds for adequate yearly progress; it also requires schools where students are failing to meet such thresholds to improve or close, while enhancing options for parents of children in such schools to place their children elsewhere. The law appears to be well conceived, addressing key problems in a sensible manner. Preliminary indications are consistent with it raising school performance and closing achievement gaps. The NCLB legislation should therefore be reauthorised. Moreover, the NCLB framework of standards, assessment and accountability should be extended through upper secondary education. That said, there are a number of areas in which improvements could be made. Though the federal government cannot set standards, it could strengthen incentives for more states to make their standards more challenging. As well, the federal government should help states and districts to better test student achievement and assess progress. An annex provides: Further evidence on school performance. (Contains 12 tables, 3 figures, 2 boxes, and 23 notes.)