This paper uses the case study method to describe the characteristics of Japanese school-based inservice teacher training programs, which are designed to help teachers improve their competence and the quality of their teaching activities. Data come from observations of and interviews with teachers in classrooms within 10 public elementary schools. School-based inservice teacher training is based on planning and conducting collaborative research activities. Teachers learn from each other, from their relationships with students, and from enhanced professional dialogue. Japanese teachers view professional development and enhancement of their teaching skills as a lifelong pursuit. They know that experience, self-study, critiques of their teaching by their colleagues, and self-reflection are important parts of this process. Rather than one-time workshops on the latest educational topics, they are engaged in a long-term process of self-reflection and development. The paper proposes a new model of improving teacher competence that consists of four interrelated teacher improvement efforts: teachers on their own (self-improvement, self-renewal, self-directed learning, self-evaluation, and self-actualization); teacher collaboration; teacher-student relationships; and teacher-parent cooperation. (Contains 42 references.) (SM)