Pervasive computing envisions seamless and distraction-free support for tasks by means of context-aware applications. Location information is a key component in many context-aware applications. This article describes the design, implementation and evaluation of LOCOSmotion, an acceleration-assisted WLAN-based tracking system. The basis of localization in LOCOSmotion is WLAN fingerprinting as proposed in RADAR [2]. In order to achieve high location update rates, it augments fingerprinting with dead-reckoning using acceleration measurements to capture movement. To evaluate the performance of LOCOSmotion, this article presents the results of a set of laboratory experiments as well as results of the EvAAL 2012 competition in Madrid. Based on the lessons learned from deploying and using LOCOSmotion during EvAAL, we identify future directions for possible optimizations.