This two-volume collection of papers reflects the four major technical advances that have revolutionized the art of well-test interpretation: the widespread use of the Stehfest algorithm for Laplace transform inversion, the exponential growth in the power of personal computers, the introduction of derivative type curves, and the development of electronic gauges. Volume I collects papers covering general well-test interpretation (including the use of derivative type curves, producing-time effects, and case histories) and special testing situations such as gas, gas/condensate, and multiphase testing; multiwell testing; and impulse testing. Volume II includes papers describing a number of popular reservoir models, including bounded reservoirs, fractured and horizontal wells, and dual-porosity and multilayer reservoirs, as well as papers on the mathematics behind the models.