Teacher collaboration through Professional Learning Communities is emerging as a key element in instructional improvement. Our definition of a Professional Leaning Community is a group of teachers prepared and supported to work regularly and collaboratively on improving classroom instruction and student learning (DuFour and Eaker, 1998). Collaboration is around learning issues evidenced by student work and defined by the group. As described in another session at this conference, the North Cascades and Olympic Science Partnership, after three years of intense professional development focused on content, instruction, collaboration, and leadership, invited Teacher Leaders to collaborate with their principals to propose, develop, and deliver a model three-day workshop to initiate Professional Learning Communities in their buildings. The resources of the partnership, especially the higher education STEM faculty, peers, and the tools introduced to the Teacher Leaders over the past three years were used to construct and implement the workshops. The activities and impact of the ongoing work of the Professional Learning Communities initiated during the summer of 2007 continue to be studied.