This part of the thematic issue focusses largely on a selection of the papers presented at a field conference of International Geological Correlation Program 427, which was held in Rouyn–Noranda in July 1999. The abstracts for the meeting are available at http://dsaing.uqac.uquebec.ca/~sjbarnes/rouyn-99. The theme of IGCP 427 is “Ore-Forming Processes in Dynamic Magmatic Systems”. Although there is a vast literature on the general geology and composition of magmatic ore deposits, relatively little has been published on the mechanics of how the deposits form. Project 427 is designed to fill this gap.