The proliferation of mobile wireless communication technology has reached a considerable magnitude. As of 2009, a large fraction of the people in most industrial and emerging nations is equipped with mobile phones and other types of portable devices. Supported by trends in miniaturization and price decline of electronic components, devices become enhanced with localization technology, which delivers, via the Global Positioning System, the geographic position to the user. The combination of both trends enables location-based services, bringing information and services to users based on their whereabouts in the physical world, for instance, in the form of navigation systems, city information systems, and friend locators. A growing number of wireless communication technologies, such as Wireless Local Area Networks, Bluetooth, and ZigBee, enable mobile devices to communicate in a purely peer-to-peer fashion, thereby forming mobile ad-hoc networks. Together with localization technology, these communication technologies make it feasible, in principle, to implement distributed location-based services without relying on any support by infrastructure components. However, the speci�c characteristics of mobile ad-hoc networks, especially the signi�cant mobility of user devices and the highly dynamic topology of the network, make the implementation of location-based services extremely challenging. Current research does not provide an adequate answer to how such services can be supported. Efficient, robust, and scalable fundamental mechanisms that allow for generic and accurate services are lacking. This dissertation presents a solution to the fundamental support of location-based services in mobile ad-hoc networks. A conceptual framework is outlined that implements mechanisms on the levels of routing, data storage, location updating, and query processing to support and demonstrate the feasibility of location-based services in mobile ad-hoc networks. The �rst contribution is the concept of location-centric storage and the implementation of robust routing and data storage mechanisms in accordance with this concept. This part of the framework provides a solution to the problems of data storage that stem from device mobility and dynamic network topology. The second contribution is a comprehensive set of algorithms for location updating and the processing of spatial queries, such as nearest neighbor queries. To address more realistic location-based application scenarios, we consider the inaccuracy of position information of objects in the physical world in these algorithms. Extensive analytical and numerical analyses show that the proposed framework of algorithms provides the necessary performance characteristics to allow the deployment of location-based services in purely infrastructureless networks. A corollary from these results is that currently feasible location-based services in infrastructure-based networks may be extended to the infrastructureless case, opening up new business opportunities for service providers.