Over the course of three rounds of consecutive funding, the National Science Foundation (NSF) invested in the Traveling Exhibits at Museums of Science (TEAMS) collaborative. Since 1996, the TEAMS collaborative museums have developed traveling exhibitions and related education materials to circulate through each other's museums, and then more broadly to the larger field of science museums. Inverness Research has served as the external evaluator on the TEAMS project for all three rounds of NSF funding. It is rare that the National Science Foundation provides funding to the same group over such an extended period of time. As the final round of funding comes to an end, we thought it important to share our perspective on the value of this investment. In this report, we will document the theory of action of the project--the rationale for the investment in and design of the project. In addition, we will summarize what we see as the return on NSF's investment, for these individual museums, their staff and visitors, and for the larger field of informal science education institutions. Finally, we will share the larger lessons learned from this long-term collaborative. (Contains 4 footnotes.)