The difficulties related to assessing students with disabilities and English language learners are not new, but the consequences of relying on scores whose accuracy cannot be ensured have become even greater because of the provisions of the No Child Left Behind Act of 2001. Under that legislation, states are responsible for tracking the academic progress of the students with disabilities and English language learners in every school. The consequences for a school of failing to ensure that these students make progress every year toward ambitious targets of performance are serious. However, regardless of that legislation or any modifications that may be made to it, the validity of test-based inferences made about the performance of students with disabilities and English language learners will be critical for those who seek to understand the academic progress of these students, as well as for those who make policies that affect them.

Under the present circumstances, the need for tests results in which users can have justifiable confidence is, if not more critical, at least more immediate. The No Child Left Behind Act requires schools and jurisdictions to take their legal obligations to assess English language learners and students with disabilities more seriously than many have done in the past. While the committee considers this renewed attention to the needs of both groups of students an important development in the effort to close persistent achievement gaps, the goal cannot be met without accurate data. Credible assessment results can play a crucial role in revealing not only where schools are failing these students, but also where they are succeeding with them. Thus it is essential that evidence of the validity of assessment results be thoroughly investigated to be sure that these results can provide useful information regarding students with disabilities and English language learners for schools, local jurisdictions, and the nation.