This three-volume set LNCS 4554-4556 constitutes the refereed proceedings of the 4th International Conference on Universal Access in Human-Computer Interaction, UAHCI 2007, held in Beijing, China in July 2007 jointly with 8 other thematically similar conferences.

The 341 revised papers presented in the three volumes were carefully reviewed and selected from numerous submissions. The papers accepted for presentation thoroughly cover the entire field of Universal Access in Human-Computer Interaction. The 117 papers of this first volume are organized in topical sections - all coping with diversity - that address the following major topics: designing for universal access, universal access methods, techniques and tools, understanding diversity: motor, perceptual and cognitive abilities, as well as understanding diversity: age.