: In this paper, we propose a group-based location service (GrLS) for mobile ad hoc networks (MANETs). The novelty of GrLS is in its exploitation of group mobility to improve the protocol efficiency. As an important mobility scenario, group mobility has many popular applications. GrLS provides different location management strategies for individual nodes and groups of nodes. An individual node recruits its own location servers and updates its location to them. On the other hand, in a set of nodes with group mobility, only the group leader recruits location servers and updates its location to a specific home region called group home region. Other members of the group are waived from performing network-wide location updates. Since the location update cost normally dominates other costs for all practical purposes, the overhead of location service is significantly reduced. Simulation results also show that GrLS can achieve higher location query success ratio with much lower overhead than e...