1. Introduction to Validity Argument in Language Testing and Assessment Carol A. Chapelle, Erik Voss; 2. Understanding Argument-based Validity in Language Testing Carol A. Chapelle, Hye-won Lee; 3. A Systematic Review of Argument-based Validation Studies in the Field of Language Testing (2000-2018) Ahmet Dursun, Zhi Li; 4. Domain Definition Inference for a Virtual Interactive Aviation English Test (VIAET) for Military Air Traffic Controllers Moonyoung Park; 5. Support for the Evaluation Inference: Investigating Conditions for Rating Responses on a Test of Academic Oral Language Hyejin Yang; 6. Generalization Inference for a Computer-mediated Graphic-prompt Writing Test for ESL Placement YunDeok Choi; 7. The Telephone Standard Speaking Test: an Outside Evaluator's Investigation of a Rebuttal to the Generalization Inference Rie Koizumi; 8. The Explanation Inference for a Test of Academic English Collocational Ability Erik Voss; 9. Extrapolation of the Meaning of Grades on Writing Tasks in an ESL Writing Class to Success on Tasks in University Courses Jooyoung Lee; 10. Justifying the Interpretation and Use of an ESL Writing Final Examination Heesung Jun; 11. An Argument for Use of a Test of Productive Grammatical Ability for Placement into Writing Classes Yoo-Ree Chung; 12. Investigating the Consequences of an ESL Placement Test Zhi Li; 13. Validation Research and its Limits Carol A. Chapelle, Erik Voss.