This report describes the results of a three-year study, the Informed Instruction Project, that investigated different approaches to mathematics instruction for students with learning disabilities and at-risk for special education services. The project focused on two strands of inquiry: (1) the effects of a computer-based diagnostic assessment system in aiding special education teachers to remedy students' arithmetic misconceptions and (2) the effects of specific curricular interventions on students in a mainstreamed setting. The three sections of the report discuss the findings. The first section presents an overview of project dissemination and products. The second section is an overview of the findings, "The Informed Instruction Project: Preliminary Findings and Implications for Future Research in Mathematics for Students with Learning Disabilities" (John Woodward and Juliet Baxter), written for the National Center to Improve Instruction in November 1995. This paper describes the implementation of a diagnostic system (TORUS) designed to detect student misconceptions in addition and subtraction that was used in a year-long, qualitative study by a special education teacher, who used direct instruction and TORUS to supplement resource room math classes. The third section contains the technical overview of the project, "Action-based Research on Innovative Mathematics Instruction and Students with Special Needs" (Juliet A. Baxter and Deborah K. Olson). (Contains references.) (Author/LC)