This proceedings contains 95 papers summarizing the current practice of soil mechanics and engineering geology in the design and construction of underground facilities. Topics are related to the design of excavation support systems; the existing precedent in various geologic environments; the development of recent excavation techniques (microtunneling); and the advance of ground modification efforts. These issues are illustrated by the description and evaluation of several well-documented case histories. Other topics relate to the basic principles in the design of underground storage of pressurized fluids, with emphasis in the selection of an appropriate location and the treatment of the excavated walls in these openings; evaluation and treatment to control surface manifestations of underground excavation; evolving natural openings; use of specialized underground construction (slurry walls) and/or materials (geosynthetics) for geo-environmental remediation; and contractual aspects of underground construction, including their interaction with the design.