The study aimed to elicit information from Vietnamese EFL university instructors about their knowledge and skills regarding the principles, theory, and practices of language assessment by means of revision and validation of the Language Assessment Literacy--Revised Vietnam (LAL-RV), which was previously developed by Kremmel and Harding (2020). A content validation study by expert review was performed and the LAL-RV was pilot tested. Drawing from a sample of 140 Vietnamese EFL university instructors, the study adopted a concurrent mixed-methods design in the form of a web-based survey. Psychometric properties of the LAL-RV were established by using exploratory factor analysis with principal axis extraction and oblique rotation. The analysis resulted in the removal of 32 of 71 initial items, leaving a two-component solution that explained 64.04% of the variance. Component one, knowledge of language assessment, was measured by 25 items, and component two, practical skills in language assessment, by another 14 items. High internal consistency was found for each subscale with Cronbach's alpha ranging from 0.96 to 0.98, indicating that the final 39-item LAL-RV was valid and reliable to measure LAL for the particular group of Vietnamese EFL university instructors. The results indicated that LAL for Vietnamese EFL university instructors consisted of two major components--language assessment knowledge and practical skills in language assessment, and that they had a moderate level of LAL (M = 3.08/5.00, SD = 0.79), corresponding to the functional level within Pill and Harding's (2013) proposed literacy continuum. At this level of LAL, Vietnamese EFL university instructors might not be professionally ready to perform assessment tasks effectively. Additionally, Vietnamese EFL university instructors' perspectives were sought concerning areas where they needed to improve their language assessment knowledge and skills. Principles of language assessment and different types of assessment were identified as the most critical areas of language assessment knowledge. The most needed language assessment skills included writing test tasks and items, designing classroom-based assessments, evaluating language tests, and interpreting/analyzing standardized test scores. The study results could inform the Vietnam Ministry of Education and Training, curriculum developers, teacher educators, and university administrators about essential language assessment topics to include in English-language teacher education curricula as well as in professional development training agendas. Continuous professional development in language assessment based on Vietnamese EFL instructors' feedback in the field will raise their levels of efficacy and support student achievement. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]