An experimental study (if the hygral expansion behavior of a wide range of laboratory produced and some commercially produced wool woven outerwear fabrics is reported. A fabric hygral expansion apparatus simultaneously measures changes in fabric length and fabric moisture regain which occur when the relative humidity of the ambient environment is altered. Fabric and yarn hygral expansion curves are analyzed and discussed in terms of the following parameters: hygral expansion coefficient (slope of the initial linear part of the hygral expansion versus moisture regain curve), hygral expansion at 25% regain, and hygral expansion at 30% moisture regain. Fabric hygral expansion behavior depends largely on the magnitude of the weave crimp. The effect of weave construction on the fabric hygral expansion is very small at high moisture regains; at low regains, plain-weave fabrics tend to show slightly higher ex pansion than the corresponding twill structures of similar crimp magnitude. The effect offiber properties on hygral expansion behavior has been examined for a series of wool plainweave fabrics produced from yarns of the same linear density. -- AATA