The purpose of this study was to examine the relationships between classroom instructional practices and computation and geometry achievement. Relationships between mathematics achievement and classroom characteristics were also explored. The sample of 1,032 students and their teachers (n=147) was selected from the 1992 Trial State Mathematics Assessment for Mississippi. The instruction-related variables included the frequent use of worksheets, small groups, and manipulatives. Additional variables included the frequent use of writing, real life problems, and assessment with problem sets. The measures of mathematics achievement used included the plausible value estimates for the numbers and operations and geometry subscales from the 1992 Trial State Mathematics Assessment. The use of hierarchical linear modeling revealed significant differences between African-American and white students in computation and geometry achievement as well as differences between male and female students in geometry. Four classroom characteristics were significantly associated with average geometry achievement. Frequent use of worksheets and assessment with problem sets were significantly associated with average computation achievement. The frequent use of writing was significantly associated with average geometry achievement. (Author)