This book contains a selection of refereed papers presented at the 1st Wo- shop on Machine Learning for Multimodal Interaction (MLMI 2004), held at the "Centre du Parc," Martigny, Switzerland, during June 21-23, 2004. The workshop was organized and sponsored jointly by three European projects, - AMI, Augmented Multiparty Interaction, http://www.amiproject.org - PASCAL, Pattern Analysis, Statistical Modeling and Computational Learning, http://www.pascal-network.org - M4, Multi-modal Meeting Manager, http://www.m4project.org as well as the Swiss National Centre of Competence in Research (NCCR): - IM2: Interactive Multimodal Information Management, http://www.im2.ch MLMI 2004 was thus sponsored by the European Commission and the Swiss National Science Foundation. Given the multiple links between the above projects and several related - search areas, it was decided to organize a joint workshop bringing together - searchers from the di?erent communities working around the common theme of advanced machine learning algorithms for processing and structuring mul- modal human interaction in meetings. The motivation for creating such a forum, which could be perceived as a number of papers from di?erent research dis- plines, evolved from a real need that arose from these projects and the strong motivation of their partners for such a multidisciplinary workshop. This asse- ment was indeed con?rmed by the success of this ?rst MLMI workshop, which attracted more than 200 participants.