An automated, real-time, reprogrammable monitoring and control system for portable, remote sensors and subjects includes one or more portable monitoring units, each of the portable monitoring units having a sensor, a location-determining device, and a sensor interface unit. Each sensor interface unit is separately configured to monitor its sensor and to transmit that sensor's data, via a digital wireless communications network, to a central monitoring device. The portable unit is carried or worn by a person or animal, or affixed to an inanimate subject.