This research aims to create and validate the quality of performance assessment using functional analysis. The researchers employed a design-based research method to create core competencies and their workload-based key outcome indicators as a preliminary study encompassing two phases, before formulating a standards-setting appraisal model to assess university lecturers in a public university, Thailand. The researchers began with documentary research to identify core competencies of university lecturers from three clusters of educational programs, namely science and technology, health science, and humanities and social sciences. An innovative prototype of university lecturers' core competencies was developed based on the obtained results from the first phase. A total of five experts and 17 users participated to validate the quality of the innovative prototype. The preliminary results reveal that there are four core competencies of university lecturers, namely teaching, research, academic service, and preserving arts and culture. Moreover, there are 13 workload-based key outcome indicators and 27 elements that resulted from the four core competencies related to the specific research university in the Thai context. Moreover, the quantitative results of the content validity index from the rating scales of the five experts indicate that the conformity index is 0.78 or higher. However, the qualitative interview results regarding the 17 users from four focus groups imply that there is a gap regarding the accuracy of current performance appraisal between lecturers' core competencies and their actual workload. Therefore, the dean should make the necessary adjustments based on the context.