Understanding mobility is important for effective clinical decision making in the area of physical rehabilitation. Ideally, a person's mobility profile in a nonclinical setting, such as the home or community, could be obtained. This profile would include the environment and context in which the mobility takes place. This paper introduces a novel wearable mobility monitoring system (WMMS) for an objective ubiquitous measurement of mobility. This prototype WMMS was created using a smartphone-based approach that allowed for an all-in-one WMMS. The wearable system is freely worn on a person's belt, such as a normal phone. The WMMS was designed to monitor a user's mobility state and to take a photograph when a change of state was detected. These photographs were used to identify the context of mobility events (i.e., using an elevator, walking up/down stairs, and type of walking surface). Validation of the proposed WMMS was performed with five able-bodied subjects performing a structured sequence of mobility tasks. System performance was evaluated by its ability to detect changes of state and the ability to identify context from the photographs. The WMMS demonstrated good potential for community mobility monitoring.