More than a decade has passed since Curriculum and Evaluation Standards for School Mathematics (NCTM 1989) and Professional Standards for Teaching Mathematics (NCTM 1991) were published, and the question of whether students' learning of mathematics has improved during that time has frequently been asked. Scores on the mathematics assessment of the National Assessment of Education Progress (NAEP), which is often referred to as "the nation's report card," foster insight into the answer to that question. NAEP is given to a national sample of students in fourth, eighth, and twelfth grades, including the lowest to the highest achieving students. In this article, the authors examine Main NAEP scores of fourth-grade students in 1990, 1992, 1996, 2000, and 2003 to trace achievement since the NCTM (1989) Standards document was introduced. They first discuss fourth graders' composite scale scores and achievement levels. Next they discuss their scores in each of the five content strands. Finally, they focus on the implications of the NAEP scores. (Contains 7 figures and 2 tables.)