International Education Journal, 2019, Volume 14, 279-287 ISSN 1443-1475 © 2019 Principal’s Leadership Behavior In Implementing Mental Revolution For Improving Teacher Performance In State 3 State School Of Kecamatan Muara Tiga Pidie Provinsi District Aceh Muhammad Yusuf Academy of Medical Records and Health Information Sihat Beurata Banda Aceh, Email: javirmaula@gmail.com Principalsare responsible for implementing mental revolutions and improving teacher performance in schools. The purpose of this study was to determine the leadership behavior of principals in implementing a mental revolution to improve teacher performance in State Junior High School 3 in Muara Tiga Sub-District, Pidie District, Aceh Province. The research duration was 3 months, from 9 January 2018 to 4 March 2018, the research applied a qualitative approach through documentation, observation, and interview data collectiontechniques. The research subjects were principals and teachers. This study shows that: (1) The formulation of the principal's policy in implementing a mental revolution to improve teacher performance in the 3 Public Middle Schools in Muara Tiga District, Pidie District, Aceh Province has made written and oral rules according to the school's vision and mission by involving teachers, school targets and the principal formulates activities to improve teacher skills. These results make teachers able to teach better so students understand more easily the lesson and can feel the comfort during school and achieve better quality education; (2) Principal program as a leader in implementing mental revolutions is to improve teacher performance in SMP Negeri 3 in Muara Tiga District, Pidie District, Aceh Province by using good communication (not rude, direct supervision, not arrogant and authoritarian), compiling KKG programs, seminars seminars and workshops with this program show encouraging results, teachers are more disciplined so they can complete their tasks well; (3) Principal Strategy as a leader in implementing mental revolution to improve teacher performance is to involve all teachers and provide direct examples and (4) Factors that influence the leadership of principals in implementing a mental revolution to improve teacher performance is their desire to improve school performance so that they have achievements better at the Aceh and national levels. It is the main factors that influence it along with other general factors, such as: the personal condition of the principal, school organization, external environment. Leadership, Principal, Mental Revolution and Teacher Performance BACKGROUND Schools as formal education institutions aim to form human beings who have personality, in developing intellectuals of students in order to educate the life of the nation. The principal as the leader of his role is very important to help teachers and employees. To improve the quality of education, a school principal must be able to improve the performance of his teachers or subordinates. Many factors can influence a person's performance, as a leader as well as a