A system and method are disclosed for recognizing and tracking a user's skeletal joints with a NUI system and further, for recognizing and tracking only some skeletal joints, such as for example a user's upper body. The system may include a limb identification engine which may use various methods to evaluate, identify and track positions of body parts of one or more users in a scene. In examples, further processing efficiency may be achieved by segmenting the field of view in smaller zones, and focusing on one zone at a time. Moreover, each zone may have its own set of predefined gestures which are recognized.