This report focuses on the participation and performance of students with disabilities on the initial administration of Minnesota's Comprehensive Assessments (MCAs). The MCAs are criterion-referenced tests used for district accountability purposes and as tools for making decisions about curriculum and instruction. Assessments in mathematics and reading were initially administered to students in third and fifth grade in 1998 and 1999. The test of written composition was administered to fifth graders only. Results from the examination indicate: (1) school district participation across Minnesota included nearly 85 percent of third and fifth graders with disabilities; (2) participation rates of students across disability categories were similar in 1998 and 1999 with students with learning disabilities, with speech/language impairments, and with emotional/behavioral disorders participating at very high rates; (3) MCAs participation of students with moderate to severe impairments was the lowest of all disability categories at 4 to 9 percent; (4) performance of third graders across all disability categories averaged about 0.5 to 1 standard deviation below the expected mean; and (5) performance of fifth graders with disabilities averaged about 0.75 standard deviation below the expected mean. Appendices include federal requirements for assessment participation and allowable testing accommodations. (CR)