Formed in July 2003, the HPSIG now has over 120 members. Its key initial focus has been to improve the Health Stream of the Annual ISD Conferences. During 2005 and 2006 the HPSIG is hosting ISDC Sunday sessions on The Dynamics of Health Reform, attended by local health policy experts as well as HPSIG members. During 2006 the HPSIG is gradually moving from an email distribution of snippets of interest to an online collaboration wiki at This continual "work in progress" includes a wikipedia on Health System Dynamics, consisting of what's been done in Health SD and a model library. The HPSIG is developing an ongoing collaborative research agenda and proposes to focus on Health System Sustainability at the ISDC2007 Boston 50th Anniversary Conference and SD presentations at future mainstream Health Policy conferences. Current Office Bearers: Geoff McDonnell, President; Gary Hirsch, Vice President and Convener of the Nijmegen Sunday Special Session; Jack Homer, Health Stream Program Chair; and Bobby Milstein, Founding Member.