The need for high-performance protective clothing systems in space, polar, and underwater operations and in industrial environments has stimulated research in clothing physiology. New, sophisticated measurement methods, some of which are going to be international standards, have facilitated this research. Measurements with subjects have validated manikin data, but have also provided information about the dynamic character and the individual variability of thermal properties of clothing under conditions encountered in the field. Manikin measurements of the basic thermal properties of clothing (insulation and evaporative resistance) have to be corrected to apply to the user situation, due to the effects of wind, posture, body movement, and moisture absorption. Evaporative heat transfer is better defined and should be incorporated in heat exchange models and thermal indices. Important aspects of clothing physiology remain to be investigated.