In-service education is considered an essential process for teachers professional development. The recent trend of educational reform in Taiwan has legislated in-service education as both an obligation and a privilege for teachers. Past research on teacher education has criticized the effectiveness of in-service education and called for comprehensive planning of teachers' in-service education. Needs assessment is an important stage of curriculum design. It is necessary to identify teachers' in-service education needs in order to have well-planned training program. The purpose of this study is to conduct a needs assessment of in-service education for secondary teachers. The research method included focus group interview and large scale survey. The members of focus group included teachers, administrators, supervisors, instruction mentors, and teacher educators. It is hoped that through this comprehensive research, the real in-service education needs of secondary teachers will be identified and a training system could be suggested.