Welcome to the proceedings of UbiComp 2004.
In recent years the ubiquitous computing community has witnessed a significant growth in the number of conferences in the area, each with its own distinctive characteristics. For UbiComp these characteristics have always included a high-quality technical program and associated demonstrations and posters that cover the full range of research being carried out under the umbrella of ubiquitous computing. Ours is a broad discipline and UbiComp aims to be an inclusive forum that welcomes submissions from researchers with many different backgrounds. This year we received 145 submissions. Of these we accepted 26, an acceptance rate of just under 18%. Of course acceptance rate is simply a measure of selectivity rather than quality and we were particularly pleased this year to note that we had a large number of high-quality submissions from which to assemble the program for 2004.