X-RAY analysis provides a new tool for solving industrial problems. It is used in many laboratories in Great Britain, and the researchers who have become expert in handling it are constantly developing new methods, and discovering new types of problem to which it can be successfully applied. The Conference arranged by the Institute of Physics, and held at Cambridge on April 10 and 11, had as its object the interchange of ideas and knowledge between the various groups of workers. Two previous attempts to call this Conference have been frustrated, the first by the onset of war and the second by the difficult conditions of the summer of 1940. In order that the object which it had in view might at any rate be partially achieved, the Institute of Physics decided to publish the series of papers which appeared in the Journal of Scientific Instruments in May and July 1941 ; these papers formed the basis of discussions for the present Conference. Some anxiety was felt by those responsible for the arrangements, lest preoccupation with war-work would prevent many from attending, but the decision to proceed was made because the X-ray tool is being widely used for problems directly connected with the War. The large attendance at the Conference (some 280 participated) and the generally expressed appreciation of this opportunity for discussion have shown that this anxiety was unnecessary.