These proceedings contain the edited papers of most of the presentations at the 26th Annual Review of Progress in Quantitative Nondestructive Evaluation (NDE) held in July 1999. The sessions covered all phases of NDE engineering from fundamentals to prototypes and included various branches of science from acoustics to x-rays. Part A of the Proceedings broadly treats subjects related to technique development in established NDE procedures, while Part B is dedicated to materials characterization, material system, and to new techniques and application. For example this year the non-linear acoustics topic included simulations from fundamental models, thermal waves, laser ultrasonics, and techniques for process control. This leading conference drew about 400 participants, with one third coming from countries outside of the US.