<p><em>Education is always been a good thing to discuss, inside there is a inseparable teacher’s role as one of the keys to the success of the applied educational system.  This research point out to the teacher’s performance influenced by competence, knowledge sharing and mediated by Organizational Citizenship Behavior. The technique to collect data is using  questionnaires where the population is a private vocational high school in West Semarang, and the respondents are the Foundation’s permanent teacher. Of all the questionnaires distributed, this study only processed 88 piece of questionnaires.  In processing the data, this study uses SPSS including validation, reliability, multiple regression, and sobel test for the mediation tests. Performance becomes the dependent variable, while competence and knowledge sharing become the independent variable, while ocb becomes the mediating variable. The conclusion of this study says that competence has no influence to Organizational Citizenship Behavior and performance. Whereas knowledge sharing has been proven has a significant influence to Organizational Citizenship Behavior and performance.  . </em></p><p><strong><em>K</em></strong><strong><em>eyword</em></strong><strong><em>s:</em></strong><em> Competence. Knowledge Sharing, </em><em>Organizational Citizenship Behavior </em><em>a</em><em>nd Teacher’s Performance</em></p>