UbiComp 2003, the 5th Annual Conference on Ubiquitous Computing, is the premier forum for presentation of research results in all areas relating to the - sign, implementation, deployment and evaluation of ubiquitous computing te- nologies. The conference brings together leading researchers, from a variety of disciplines, perspectives and geographical areas, who are exploring the impli- tions of computing as it moves beyond the desktop and becomes increasingly interwoven into the fabrics of our lives. This volume, the conference proceedings, contains the entire collection of high-quality full papers and technical notes from UbiComp 2003. There were 16 full papers in this year's conference, selected by our international program committee from among 117 submissions. There were also 11 technical notes in the program: 8 taken from the 36 technical note submissions, and 3 that were adapted from full paper submissions. We are very grateful to Tim Kindberg and Bernt Schiele, our Technical Notes Co-chairs, and to all the authors and reviewers of both papers and technical notes who contributed to maintaining the high standards of quality for the conference. In addition to the full papers and technical notes, UbiComp 2003 also p- vided a number of other participation categories, including workshops, dem- strations, interactive posters, a panel, a doctoral colloquium and a video p- gram. While accepted submissions in these categories were also of high quality, timing and size constraints prevented us from including them in this volume.

Location and Space.- Building World Models by Ray-Tracing within Ceiling-Mounted Positioning Systems.- On a Location Model for Fine-Grained Geocast.- RightSPOT: A Novel Sense of Location for a Smart Personal Object.- User-Friendly Surveying Techniques for Location-Aware Systems.- Modeling and Inference.- Sto(ry)chastics: A Bayesian Network Architecture for User Modeling and Computational Storytelling for Interactive Spaces.- Inferring High-Level Behavior from Low-Level Sensors.- Activity Zones for Context-Aware Computing.- Context Awareness.- Context-Aware User Authentication - Supporting Proximity-Based Login in Pervasive Computing.- Secure Spontaneous Device Association.- AwareCon: Situation Aware Context Communication.- liquid: Context-Aware Distributed Queries.- Is Context-Aware Computing Taking Control away from the User? Three Levels of Interactivity Examined.- New Devices and Technologies.- Tools for Studying Behavior and Technology in Natural Settings.- Very Low-Cost Sensing and Communication Using Bidirectional LEDs.- SPECs: Another Approach to Human Context and Activity Sensing Research, Using Tiny Peer-to-Peer Wireless Computers.- A 2-Way Laser-Assisted Selection Scheme for Handhelds in a Physical Environment.- Domestic Environments and Healthcare.- Finding a Place for UbiComp in the Home.- New Perspectives on Ubiquitous Computing from Ethnographic Study of Elders with Cognitive Decline.- Practical Considerations of Context for Context Based Systems: An Example from an Ethnographic Case Study of a Man Diagnosed with Early Onset Alzheimer's Disease.- "Playing with the Bits" User-Configuration of Ubiquitous Domestic Environments.- Social Aspect and Privacy.- IntelliBadgeTM: Towards Providing Location-Aware Value-Added Services at Academic Conferences.-UbiTable: Impromptu Face-to-Face Collaboration on Horizontal Interactive Surfaces.- Social Network Computing.- The Design of a Context-Aware Home Media Space for Balancing Privacy and Awareness.- New Interfaces.- Context-Aware Computing with Sound.- An Architecture and Framework for Steerable Interface Systems.- Evaluation of Visual Notification Cues for Ubiquitous Computing.