Each of the three parts of this report provides a somewhat different perspective on U.S. students' knowledge and understanding of U.S. history. Part 1 summarizes the assessment performance of approximatley 16,0000 fourth-, eighth-, and twelfth-grade students based on the National Assessment of Educational Progress U.S. history proficiency scale. Chapter 1 uses this measure to summarize the levels of proficiency displayed by students in the 1988 assessment, offering an overview and examples of their knowledge and understanding. Chapter 2 compares U.S. history proficiency across the grades and across subpopulations defined by race/ethnicity, gender, region, and other characteristics. Part 2 of the report takes a closer look at the assessment results. The chapters in this section provide information not only on the results of the assessment of students in grades 4,8, and 12, but also on trends in the performance of approximately 2,300 eleventh-grade students, based on a special study conducted in 1986 and 1988. Chapter 3 explores students' knowledge of historical periods, chronology, documents, and persons, while chapter 4 summarizes their familiarity with the historical contexts of political and economic life as well as of cultural, social, and family life. Part 3 describes the amount and nature of social studies and U.S. history instruction reported by students who participated in the 1988 assessment and in the special trend assessment. Chapter 5 summarizes the extent of students' instruction in these subjects, and chapter 6 reports on various aspects of this instruction--particularly the topics studied and the prevalence of various instructional activities. Many tables of statistical data are included. (JB)