and Optimization (CADO), Department of Mathematics and Statistics, The University of Western Australia, Perth, from 29 to 30 June 1998. This is the first time the OD mini-conference has been held at the west­ ern coast of Australia. This fifth OD preceded the International Conference on Optimization: Techniques and Applications (ICOTA) held at Curtin Uni­ versity of Technology. Many participants attended both events. There were 28 participants in this year's mini-conference and 22 presentations in the mini­ conference. The presentations in this volume are refereed contributions based on papers presented at the fifth Optimization Days mini-conference. The volume is di­ vided into the following parts: Global Optimization, Nonsmooth Optimization, Optimization Methods and Applications.