Purpose: To provide an analysis of the accuracy and effectiveness of using the Clinical Evaluation of Language Fundamentals-Fourth Edition (CELF-4) to identify students as having language-based disabilities. Method: The CELF-4 is analyzed within the current standards set by the federal law on special education, the available research, preferred practice guidelines, and the statistical information provided in the CELF-4 Examiner's Manual. This study also analyzes the accuracy and effectiveness of the CELF-4 from varying perspectives such as English Language Learners, students who speak dialects other than Standard American English, economically disadvantaged students, and students with motor, attention, and memory limitations. Conclusions: Despite the widespread use of the CELF-4 as a primary diagnostic tool in disability determinations, construct validity especially in its discriminant accuracy is weak; significant bias issues exist in many subtests especially for English Language Learners and speakers of dialects other than Standard American English; and standardization based on the U.S. census is unlikely to reflect the language norms of a student's speech community which is the standard for identifying a language disability. Nonetheless, student performance on the CELF-4 can provide insight regarding a student's strengths and weakness that may be useful as part of a disability determination. Particular CELF-4 subtests provide valuable information about a student's language skills but disability determinations based on scaled scores or standard scores derived from the CELF-4 should be avoided. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]