This study aims to examine the relationship between the independent variables: Principal' Supervision, Work-Discipline and Pedagogic Competence with dependent variables of Quality of Teachers' Work. The research employed a proportional sampling random sampling in 284 civil servants in Junior High School Teachers in Jambi, Indonesia. This study was conducted using sequential explanatory mixed methods that prioritize research with quantitative methods and followed by qualitative methods to obtain the deep and comprehensive results. In this study, we concluded that: (1) there is a positive and significant relationship between the Principal's Supervision with the Quality of Teachers' Work, (2) there is a positive and significant relationship between Working Discipline with Quality of Teachers' Work, (3) there is a positive relationship between Pedagogic Competence with Quality of Teachers' Work (4) there is a positive and significant relationship between the Principal' Supervision, Work Discipline and Pedagogical Competence together with the quality of Teachers's Work with determination coefficient 0.5143 and the regression equation y = 7.373 + 0,286X₁ + 0,388X₂ +1,643X_3. This research was supported by the results of qualitative analysis that 51.4% of teacher quality is determined by the principal's supervision, work discipline and pedagogical competence.