The session on the Dynamics of Health Reform, hosted by the Health Policy Special Interest Group (HPSIG), will focus on factors promoting and resisting change in different countries' health care systems, possible unintended consequences of reform efforts, and potential leverage points for achieving significant reform. The session builds on insights developed in a session at the 2005 ISDC in Boston. This year, the session will begin with brief presentations of a number of papers that address health care system change and reform in several countries and at scales ranging from neighborhoods in cities to regions and states to an entire country. After these presentations, attendees will discuss common features across these several countries and scales, as well as from their own countries, and synthesize some useful "rules of thumb" for health reform that benefit from a dynamic perspective. We hope to also have some local experts from the Netherlands in attendance who can draw on their country's recent experience with reform. The balance of the session will be spent on thinking about next steps for the HPSIG, further development of its web site and Wikipedia, and potential focus for a session at the 2007 ISDC.