This paper describes an improved steel-ring test method for determining tensile stresses induced by the restrained shrinkage of either mortar or concrete. The method permits measurement of shrinkage stresses at ages as early as five hours after casting. The specimens used were 102-mm (4-in.) thick rings with an outer diameter of 660 mm (26 in.). Graphic data are presented to validate the efficacy of the method. Restrained shrinkage measurements are given for plain mortar, mortar incorporating alkali-resistant glass fibers, and plain concrete (both normal weight, incorporating gravel aggregate, and lightweight, incorporating expanded slate aggregate). Also shown are the effects of heat of hydration associated with special hydraulic cements (aluminous and ultrafine Type I portland).