Maps are often used as decision support tools in both, desktop geographic information systems (GIS) and mobile GIS environments. The decision support capabilities of current location-based services (LBS) are limited to navigation support and database querying with no analytic evaluation of the attractiveness of alternative destinations being offered. This chapter demonstrates how LBS can be extended with specific decision support functionality, namely multi-criteria decision analysis (MCDA). MCDA was recently transferred to the mobile GIS platform illustrating how LBS user preferences can be represented by the parameters in a MCDA method and will lead to personalized decision outcomes. An extension to a collaborative crisis management scenario is proposed, in which mobile decision-makers have MCDA tools at hand to help them make more informed choices. This chapter describes the scenario and derives a client/server architecture as well as the user interface and map design for a mobile decision support system for emergency response.