Passive dosimeters have been extensively used to measure space radiation exposures to crewmembers for over three decades. Although a significant evolution in materials, processes, readout, and analysis techniques for these sensors has been witnessed during this period, these simple devices remain the backbone of the current operational dosimetry program for the Space Shuttle. Indeed, the utilization of passive dosimeters is also planned for the space station as well as advanced manned exploration programs, i.e., Lunar Base and Mars missions. Sensor materials and types have included thermoluminescent dosimeters, radiation-sensitive films and emulsions, and plastic nuclear track detectors. Early, transitional, and current passive dosimeter materials, systems, and techniques to measure space radiation are described and discussed, with major emphasis on the development of thermoluminescent dosimetry (TLD) techniques. Results of thermoluminescent passive dosimeter measurements on the Space Shuttle to date are presented and discussed. Applications of passive dosimeter data to modify existing space radiation environmental and shielding models are examined. Accuracy and precision of passive techniques for environmental monitoring are developed and discussed. Finally, specific recommendations for future research with passive radiation dosimeters are presented.