Language Accommodations for English Language Learners in Large-Scale Assessments

How do we create accurate assessments of students' abilities when their experiences with a particular academic subject have been in another language? If we account for this difference using accommodations, do the accommodations themselves have an unintended impact on the results? A study by the National Center for Research on Education, Standards, and Student Testing (CRESST) at the University of California, Los Angeles, measures the effectiveness, validity, differential impact, and feasibility of accommodations for ELLs as used on a NAEP science test and an English reading proficiency test.