In the spring of 1985, the Oregon Department of Education conducted an assessment of eighth grade students' skills in writing, reading, and mathematics. This report provides results for the mathematics portion of the assessment under these headings: (1) arithmetic skills; (2) estimation; (3) geometry and measurement; (4) application; (5) problem-solving; (6) percent, ratio, proportion, and probability; (7) score differences based on gender; and (8) use of a calculator. In addition, information on test development, test design, test administration, and on scoring and reporting is provided. Also included are highlights of findings and recommendations. Among the findings are those showing that the general level of mathematics achievement among Oregon eighth graders is greater than 60 percent of students nationally, that student performance in arithmetic skills was at an excellent level (with the exception of basic operations involving fractions), and that student performance in estimation and probability was lower than desired (with more emphasis recommended, including inservice programs to upgrade teaching skills related to both of these skill areas). One of the recommendations offered is to train and use mathematics resource teachers and to implement peer coaching strategies to assist teachers in the instruction of low performance areas. Appended are a statewide summary report and a sample school summary report.(JN)