This fourth workshop in the series of workshops on 'HCI in Mobile Guides' once again aims to bring together both researchers and practitioners who develop and evaluate mobile guides, i.e. systems designed to guide a user who is moving in a physical environment by giving directions and supplying relevant information and access to services via some form of mobile device. Application examples of mobile guides include: mobile tourism services, museum/exhibition guides, support for building communities and context-aware directory services. The particular focus of this workshop is on establishing guidelines for fostering the development of usable mobile guide systems based on practical experience and evaluations. Following review by the program committee, accepted papers will be presented and discussed at the workshop.