The National Assessment of Educational Progress (NAEP) is the only nationally representative and continuing assessment of what students in the United States know and can do in various academic subjects. The 1996 NAEP in mathematics assessed the current level of mathematical achievement as a mechanism for informing education reform. In 1996, 44 states, the District of Columbia, Guam, and the Department of Defense schools took part in the NAEP state mathematics assessment program. The NAEP 1996 state mathematics assessment was at grade 4 and grade 8, although grades 4, 8, and 12 were assessed at the national level. The 1996 state mathematics assessment covered the five content strands: (1) Number Sense, Properties, and Operations; (2) Measurement; (3) Geometry and Spatial Sense; (4) Data Analysis, Statistics, and Probability; and (5) Algebra and Functions. In Missouri, 2,643 students in 107 public schools and 449 students in 23 nonpublic schools were assessed at the fourth-grade level and 2,386 students in 105 public schools and 353 students in 22 nonpublic schools were assessed at the eighth-grade level. This report describes the mathematics proficiency of Missouri fourth- and eighth-grade students, compares their overall performance to students in the Central region of the United States and the entire United States (using data from the NAEP national assessment), presents the average proficiency for the five content strands, and summarizes the performance of subpopulations (gender, race/ethnicity, parents' educational level, Title I participation, and free/reduced lunch program eligibility). Results are also presented for nonpublic school students at grades 4 and 8 for the 1996 state mathematics assessment. To provide a context for the assessment data, participating students, their mathematics teachers, and principals completed questionnaires which focused on: school characteristics (attendance); instructional content (curriculum coverage, standards, amount of homework); delivery of mathematics instruction and its characteristics; use of technology in mathematics instruction; students' own views about mathematics; and conditions facilitating mathematics learning (hours of television watched, parental support, home influences). On the NAEP fields of mathematics scales that range from 0 to 500, the average mathematics scale score for fourth grade students in Missouri was 225 compared to 222 throughout the United States and the average mathematics scale score for eighth grade students in Missouri was 273 compared to 271 throughout the United States. The average mathematics scale score of fourth and eighth grade males did not differ significantly from that of females in either Missouri or the nation. At the fourth and eighth grades, White students in Missouri had an average mathematics scale score that was higher than that of Black and Hispanic students. (ASK)