The changing of the context of age and the characteristics of today's generation demand a role of a teacher to be more creative and innovative. A way to answer this need is to cultivate the knowledge sharing behavior (KSB) in the school environment. There are many factors that can support the establishment of this KSB, including transformational leadership, trust and self-efficacy. This study aims to determine the effect of transformational leadership, trust and self-efficacy on KSB of the teachers. The research subjects were 112 teachers who teach in two locations of XYZ Private High School in Jakarta Barat which has the potential to develop KSB. The design used in this study was PLS-SEM with a quantitative approach. The results of this study showed that transformational leadership and self-efficacy affected KSB positively, whereas trust didn‟t affect KSB positively. / Perubahan konteks zaman dan karakteristik generasi zaman sekarang menuntut peran guru yang semakin kreatif dan inovatif. Salah satu upaya untuk menjawab hal ini adalah dengan membudayakan perilaku knowledge sharing behavior (KSB) di lingkungan sekolah. Ada banyak faktor yang dapat mendukung terbangunnya perilaku KSB ini, di antaranya transformational leadership, trust dan self-efficacy. Penelitian ini bertujuan untuk mengetahui pengaruh transformational leadership, trust dan self-efficacy terhadap KSB guru. Subjek penelitian adalah 112 guru yang mengajar di dua lokasi Sekolah Menengah Atas Swasta XYZ di Jakarta Barat yang memiliki potensi untuk membangun perilaku KSB. Desain penelitian yang digunakan adalah PLS-SEM dengan pendekatan kuantitatif. Hasil penelitian yang diperoleh memperlihatkan bahwa transformational leadership dan self-efficacy mempengaruhi KSB secara positif, sedangkan trust tidak mempengaruhi KSB.