This book presents practices currently used in the design and installation of monitoring wells. Emphasis is placed on the constraints dictated by hydrogeology conditions and limitations imposed by the availability of equipment to do the work that is needed. These constraints are balanced against the need to construct a well that will allow sampling, testing, and introduction of necessary tools. A matrix is provided to assist in the evaluation of drilling techniques. Procedures for equipment decontamination, well installation and completion, well development, well management, and well abandonment are discussed.