The members of the Health Policy SIG agreed at the Oxford conference in 2004 to begin a collaborative effort to examine national health care system reform from an SD perspective. The first product of this collaboration is a paper being presented at one of this year’s parallel sessions, entitled “Achieving health care reform in the United States: Toward a whole-system understanding.” The paper includes a series of causal loop diagrams laying out an initial theory of why reform efforts have largely failed in the U.S. and outlining the characteristics of more effective reform. This paper was recently distributed to all HPSIG members for their comments, and also to some U.S. health system experts from outside SD. During the special Sunday afternoon session we will review the comments we have received and also hear directly from a few of the outside experts who are able to join us in person. We will also look to non-U.S. HPSIG members for an international perspective, and talk about how we can best expand our collaboration both internally and externally during the year to come.