This report describes findings from the second year of the most comprehensive, intensive, and carefully constructed study to date of trends in student achievement in all 50 states since 2002, the year the No Child Left Behind Act (NCLB) was enacted. Last year, the Center on Education Policy (CEP), an independent nonprofit organization, began this work by seeking to answer the question of whether student achievement has increased "because" of NCLB. The authors soon discovered that it is not possible to directly relate changes in student achievement to NCLB, as they explain later. However, it is possible to learn much more about student achievement now than it was before 2002, when NCLB was enacted, because the law has greatly expanded student testing, accountability, and reporting of test scores in elementary and secondary schools. This second year of their study therefore looks at test score trends since 2002. To carry out this study, CEP collected, verified, and analyzed a vast array of state and national test data. This year's study continues the focus on two main questions--whether reading and math achievement has increased since 2002 and whether achievement gaps between subgroups of students have narrowed. Five main conclusions emerged from their analyses. These are: (1) Since 2002, reading and math achievement on state tests has gone up in most states according to the percentages of students scoring at the proficient level; (2) Trends in reading and math achievement on NAEP (National Assessment of Educational Progress) have generally moved in the same positive direction as trends on state tests, although gains on NAEP tended to be smaller than those on state tests; (3) In states with sufficient data to determine achievement gap trends on state tests, gaps have narrowed more often than they have widened since 2002, particularly for African- American students and low-income students; (4) Gaps on NAEP have also narrowed more often than they have widened in states with sufficient data to determine gap trends; and (5) It is impossible to determine the extent to which these trends in test results have occurred because of NCLB. Appendices include: (1) Study Methods; and (2) More about Standard Deviations and Relationships of Gaps to Cut Scores. (Contains 9 figures, 3 boxes and 62 tables.