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 115 papers of this second volume are devoted to ambient interaction and are organized in topical sections on intelligent ambients, access to the physical environment, mobility and transportation, virtual and augmented environments, as well as interaction techniques and devices.