Abstract: This study aimed to develop the internal quality assurance system for the Faculty of Education, The National University of Laos. The study was conducted using the mixed-methods process by the uses of survey research and research and development. Data were collected from documents and the Department of Education personnel comprising the Faculty dean, academic affairs division head and assistant head, student activities division head, 4 department assistant heads, agency heads and 10 instructors. Documents and related literature were studied for constructing a questionnaire for 13 experts to provide opinions. Delphi technique was employed for summarizing experts opinions, which were in congruence with one another to construct a manual of the internal quality assurance system for the Faculty of Education, The National University of Laos. The manual was discussed in the seminar by referencing 9 experts. The instruments used were an interview form, an open-ended questionnaire and a 5-rating-scale questionnaire. The statistics used for analyzing the collected data were mean, standard deviation, median and interquartile range. The results of the study were as follows: For the condition before development, the Faculty of Education, The National University of Laos had not yet had a clear education quality assurance system. The developed education quality assurance system for the Faculty of Education, The National University of Laos consisted of these 3 aspects: input, process and product. Input had 10 factors: philosophy, vision, purposes, operational plan, administrator, finance and budget, instructors, students, curricula and buildings and spaces and instructional media, with 44 indicators. Process had these 7 factors: administering process, learning and teaching process, measuring and evaluating process, student development process, human resource administration and development process, quality assurance process and relationship with product user process, with 34 indicators. And product had 5 factors: university graduates characteristics, research works and academic works, academic services to society, art and culture maintenance works and faculty reputation, with 8 indicators. Operational mechanisms for internal quality assurance included: determination of the national-level policy, determination of agencies and responsible personnel consisting of academic affairs section with the responsible committee and determination of quality assurance activities every 5 years.