The guiding principles of the ACP have remained virtually unchanged since its inception fifty years ago, but essentially the ACP is in a slow but constant state of evolution in response to external and internal change. It is an organization that takes itself for granted rather than being impressed that it works as well as it does. The occasion of the ACP's fiftieth birthday is not only a time to look back on our achievements and forward to the challenges that await us, but also to take stock of the contribution of so many of our members to the work of the ACP, that has been and continues to be carried out with the amazing