Residual stresses can be defined as those stresses that remain in a body after manufacturing or processing in the absence of external forces or thermal gradients. Virtually all manufacturing and fabricating processes introduce residual stresses into the manufactured article and extreme service loading may also change the state of residual stress in the component. The effects of residual stress may be either beneficial or detrimental, depending upon the sign, magnitude and distribution of the stress. For improved process and product control, design, performance and modelling it is increasingly important to have rigorous experimental procedures to determine the residual stresses to the best possible accuracy. A wide variety of residual stress measurement techniques exist, but without experience or detailed knowledge it is difficult for the user to choose which method is most appropriate. This is the third NPL Good Practice Guide dealing with Residual Stress Measurement, the others, which are also available, focus on the X-ray Diffraction and Hole Drilling methods.