From its inception, the department placed work with science teachers all over the country as one of its main priorities, under the belief that such work is one of the most effective ways to influence science education. The department implements a special pre-service program for students of the Weizmann Institute. In addition to the traditional support of specific new programs, the department enacts a variety of in-service professional-development frameworks that provide opportunities for continuous learning and growth, and for the professionalization of science teachers. The development of innovative frameworks for continuing professional development of teachers builds on existing knowledge about effective ways to work with teachers and on research carried out by members of the department. The various disciplinary teams cooperate in the design of models for teacher development; implement them in their disciplinary areas and exchange results and insights. Some of the professional development activities are carried out collaboratively by multidisciplinary teams. The programs enacted by the department focus on updating the teachers’ knowledge base (for example, by taking advantage of the expertise of Weizmann Institute scientists) and their knowledge of mathematics and science education. A central goal is to enable teachers to become independent users of available resources relevant to the teaching profession. The programs are contextualized in teachers’ practice and build on collaborative reflection on evidence brought from classes on existing practices and on experimenting with new pedagogical models towards considering the introduction of changes in practices. The department is active in establishing and studying different formats of teachers’ learning communities.