To develop a thermostatic fabric, a 100% polyester fabric is treated with octadecane- containing microcapsules by a knife-over-roll coating process. The amount of heat content increases as the concentration of microcapsules increases. and it decreases as the temper ature and time increase. The surfactant treatment at a given microcapsule concentration increases the heat content of the treated fabrics about 56-94%. The durability of the coated microcapsules lasts for about ten launderings. The treated fabric becomes stiffer and less smooth, soft, and full than the untreated fabric, as shown by KES measurements. Wear trials with the untreated and treated garments in a conditioned environment confirm the temperature sensing properties of treated garments. The cooling effect from thermal storage of the octadecane-containing microcapsules is revealed by results showing that the changes in the mean skin and microclimate temperature with the treated garment are less than for those wearing the untreated garment.