This is the twelfth annual report by the National Center on Educational Outcomes (NCEO) analyzing public reporting of disaggregated assessment data for elementary and secondary students with disabilities in the United States. Reporting disaggregated performance data at the state and district level to the public is required of states by the Individuals with Disabilities Education Act (IDEA); the 2007-2008 school year marks the ninth annual reporting period since this requirement was established, and the sixth reporting period since the 2001 reauthorization of the Elementary and Secondary Education Act (ESEA). For the 2007-2008 school year, the number of regular states publicly reporting disaggregated data for both participation and performance for students with disabilities taking regular assessments fell from 46 to 45. Thirty-six states provided disaggregated participation and performance data for students with disabilities taking alternate assessments based on alternate achievement standards (AA-AAS) for 2007-2008; this number remained the same as in 2006-2007. Reporting of regular assessments in the ESEA accountability system, by type, for regular states showed a pattern similar to 2006-2007, with 100% reporting participation and performance on norm-referenced tests (NRT), combination NRT and criterion-referenced tests (NRT/CRT), and exit exams (EXIT), but lower levels of reporting on the most common test type, CRTs. Although a greater number of CRTs were used, the percentage of those on which states reported fell from 89% to 85%. Reporting on regular assessments was provided by 49 regular states in 2007-2008, the same number as in 2006-2007. Reporting on AA-AAS was provided by 43 regular states in 2007-2008, down from 44 states in 2006-2007. For the unique states, four reported both participation and performance data for regular assessments. One unique state reported both participation and performance data for AA-AAS. The public reporting of participation and performance for 2007-2008 assessments was fairly consistent with the reporting in 2006-2007. There continues to be a need for states to report clearly, to publicly report on accommodations use, and to strive to make the data that are reported accessible to those who seek them via public Web sites. Appendices include: (1) Example Letter to Assessment Director; (2) Example Letter to Special Education Director; (3) Status of Disaggregated Data (Participation and Performance) for Students with Disabilities on Regular State Tests in the Fifty States and Unique States for 2007-2008; (4) Status of Disaggregated Data (Participation and Performance) for Students with Disabilities on State Alternates Based on Alternate Achievement Standards (AA-AAS) in the Fifty States and Unique States for 2007-2008; (5) Status of Disaggregated Data (Participation and Performance) for Students with Disabilities on Alternates Based on Modified Achievement Standards (MAS) in the Fifty States for 2007-08; (6) Disaggregated Participation Information for Students with Disabilities on Regular State Tests for the Fifty States and Unique States for 2007-2008; (7) Disaggregated Alternate Assessment Participation Information for Students with Disabilities on Regular State Tests for the Fifty States and Unique States for 2007-2008; (8) Disaggregated Regular Assessment Performance Information for Students with Disabilities for the Fifty States and Unique States for 2007-2008; (9) Disaggregated Alternate Assessment Performance Information for Students with Disabilities for the Fifty States and Unique States for 2007-2008; and (10) Participation and Performance for Students Tested with Accommodations for 2007-2008. (Contains 9 tables and 21 figures.)