This book constitutes the refereed proceedings of the 6th International Symposium on Mobile Human-Computer Interaction, Mobile HCI 2004, held in Glasgow, UK, in September 2004. The 25 revised full papers, 20 revised short papers, and 22 revised posters presented together with summaries of 7 workshops and 2 panels were carefully reviewed and selected from a total of 166 submissions. The full papers are organized in topical sections on screen and power limitations; user differences and navigation; evaluation and evaluation techniques, till, touch and text entry; auditory interactions; device differences and web pages; and novel interaction techniques.