A wide range of assistive and rehabilitative technologies (ART) are available to assist with mobility and upper limb function. However, anecdotal evidence suggests many of the devices prescribed, or purchased, are either poorly used, or rejected entirely. This situation is costly, both for the healthcare provider and the user, and may be leading to secondary consequences, such as falls and/or social isolation. This paper reports on the development and initial feasibility testing of a system for monitoring when and how assistive devices are used outside of the clinic setting, and feeding this information to the device user themselves and/or prescribing clinician (where appropriate). Illustrative data from multiple time-synchronized device and body worn sensors are presented on a wheelchair user and a user of a 'rollator' walking frame, moving along a walkway. Observation of the sensor data in both cases showed characteristic signatures corresponding to individual 'pushes'. In parallel with this work, other project partners are exploring clinician and patient data requirements, as well we sensor set acceptability The initial results highlight the potential for the approach and demonstrate the need for further work to reduce and optimize the sensor set.