The Schmidt rebound hammer has now been in general use for longer than a decade. A lot of experience in its use has accumulated but areas of dispute remain although certain facts are universally accepted. A recent consensus of international opinion stated that the hammer provided only a rough indication of the quality of concrete but that it was nevertheless useful or very useful. With this conclusion in mind, an attempt is made to summarize practice on which a measure of agreement exists. In cases where it is required to compare concrete of one quality with another quality, the Schmidt rebound hammer has found very wide application. Confidence in the hammer under such condition of testing is well founded, especially when comparing concretes of similar age, surface, and history. When using the hammer as a device for quality control in production, emphasis is shifted away from the concrete towards the variables in the production process as they are reflected in the readings of the hammer. The standard of quality is fixed from previous knowledge of the requirements or from specific tests. It is normally not necessary to translate the reading of rebound number in terms of the correlated property. Frequently, as a result of change in curing temperature, properties of cement, or mix proportions, it may be difficult to estimate the earliest time of shrinkage molds or formwork or transferring prestress. Calibration of a minimum rebound number against a condition of the unit based on experience, or a condition in terms of cube strength, can be of great help in taking such decisions. The hammer can also be useful for carrying out a collateral test with a small number of specimens tested destructively. The hammer permits a greater number of test to be carried out at low cost over the whole of the unit.