Localization is a fundamental problem in wireless sensor networks. In this paper, we consider how to localize individual nodes in a wireless sensor network when some subset of the network nodes can be in motion at any given time. For situations in which it is not practical or costefficient to use GPS or anchor nodes, this paper proposes an Anchor-Free (AF) Mobile Geographic Distributed Localization (MGDL) algorithm for wireless sensor networks. Taking advantage of the accelerometers that are present in standard motes, MGDL monitors a moving distance for each node, then uses a procedures to detect any movement of each node. If movement is detected, then the moved node will trigger a series of mobile localization procedures to recalculate and update the location locally, such procedures will be stopped while the node stops moving. Data collected using Tmote Invent nodes (Moteiv Inc.) and simulations show that proposed detection method can efficiently detect the movement, and that the ...