This study aims to determine the effect of learning discipline on the mastery of mathematical concepts. There are two variables in this study, namely learning discipline and mastery of mathematical concepts. The research method used is a survey. A sample of 82 students was selected from three schools, namely Vocational High Schools in Jakarta, Indonesia. Data was collected using questionnaires and test techniques. The results showed that there was a significant influence of learning discipline on the mastery of mathematical concepts. In accordance with the results of the study, it showed that student learning discipline had an influence on mastery of mathematical concepts. Thus, student learning discipline must be implemented consistently both at school and at home. This study provides input to the world of education that overall mastery of mathematical concepts in students requires consistent practice questions, to do practice questions requires a high learning discipline attitude. Disciplining children requires cooperation between teachers, parents, and the environment.

Keywords : Learning Discipline; Concept Mastering; Mathematics; Vocational High School.