The purposes of this research were 1) to study the compositions of the Structural Equation Model for goodness competency development according to Buddhist principles of students in secondary schools, 2) to develop the structural equation model for goodness competency development according to Buddhist principles of students in secondary schools, and 3) to propose the structural equation model for goodness competency development according to Buddhist principles of students in secondary schools. Multiphase mixed methods research was designed by using quantitative methods to extend qualitative results. It was divided into 3 phases. Phases 1-2 used qualitative research, the key informant was 4 educators and 10key informants from monks, school administrators and teachers who participated in the project including 9 experts for focus group discussion. They were selected by purposive sampling. Data were analyzed by using analytic induction. Phase 3 used quantitative research, the sample group consisted of 470 samples.