The purpose of this research is to study and to compare both teachers? and students? opinions towards the Conduct of Secondary-level Disciplinary Affairs Department at Thai Christian School in Bangkok.  Numerous variables were measured in this study including : gender, educational qualification, experience, class level, and students? grade point supervision on students, discipline of students, prevention and correction of inappropriate behavior, virtue and ethics, and classroom management. 
The participants in this study were fifty-six teachers and one hundred and ninety-four students from Thai Christian School. The instrument implemented in collecting data was a 50 -item questionnaires of five rating scales. The formulas used in the data analysis were mean, standard deviation and t -test
The results of the research showed that the teachers? opinion projected the variable of discipline in the moderate level. The highest mean was in virtue and ethics and the lowest mean was in student discipline. According to the students? opinions, overall performance was also in the moderate level. The highest mean was in the student discipline, and the lowest mean was in the student supervision.
Regarding the comparison of the teachers? and students? opinions on the conduct of the disciplinary affairs performance, and the variables of: gender, educational qualification, experience, class level, and students? grade point average, in conclusion there were no difference in the aspects, but the comparison of teachers?  experiences was significantly different at the .05  level in virtue and ethics.
