This volume contains the peer-reviewed papers accepted for presentation at the 18th Australasian Conference on the Mechanics of Structures and Materials held in Perth, 2004. Papers contained describe significant advances in a large number of diverse areas, indicating the range of applications of the basic principles and techniques of mechanics from traditional areas such as steel and concrete structures, through to modern areas such as structural health monitoring and structural rehabilitation using carbon fibre composites. With topics ranging from foundation piles to shaken baby syndrome, this volume reports the results of countless thousands of hours of research and millions of dollars of research funding.