The development and use of the Web by science-technology museums, mass media, and other informal science learning resource centers to enable remote public access to their resources and expand their educational outreach programs has grown enormously over the past decade. Similarly, many "open source" learning and education portals are rapidly growing into major free global lifelong learning resources. At the same time, U.S. student achievement in science in middle and high schools continues to be lag far behind that of students in many developed countries, and many American K-8 science teachers still lack B.A. degrees in science or adequate ongoing professional development in both science content and pedagogy. A huge and growing gap thus exists between the vast, freely available wealth of museum and other informal science Web learning resources and teachersí integral use of these rich resources to improve studentsí science learning and achievement. The Bay Area Science Museum and Education Collaboratory has been designed to help bridge this gap. The design rationale, methodology, web architectural components, and teacher professional development and support model of the Bay Area Collaboratory are briefly outlined, as well as a summary of formative evaluation results over the past five years. The potential of expanding this web-based regional museum education and teacher professional development collaboratory model to other geographic areas, as well as to other kinds of museums and curricular content, is also explored.