Schools in the United States serve a linguistically diverse population of students. The U.S. Department of Education estimates that 9.1 percent of public school students in the United States were English learners (ELs) in 2014-2015. These are students who meet the federal definition of English learners, referred to in the Individuals with Disabilities Education Act (2004) as limited English proficient (LEP), and formerly referred to as LEP in the Elementary and Secondary Education Act of 1965 (Sec. 8101), or more recently as English language learners (ELLs), prior to their designation as ELs in the Every Student Succeeds Act (ESSA) of 2015. Roughly 14% of ELs had a disability in 2014-2015 (U.S. Department of Education). ELs with disabilities may require increased capabilities in school professionals and education agencies to meet their needs to learn English skills at the same time they are acquiring content and expectations for behaviors or functioning in schools. These students, by definition, are students who must progress toward proficiency in speaking, reading, writing, or understanding English; they also have one or more disabilities that affect their academic and behavioral functioning and possibly their acquisition of the English language. Documenting how educators and policymakers can determine the degree of progress in English proficiency that ELs with disabilities are making poses a significant problem. The purpose of this report is to review the literature on methods for measuring English language proficiency (ELP) "progress" for ELs with disabilities.