This book describes the latest methods and practices in the field of subsurface drainage for slope stability. Groundwater pressure significantly affects slope stability; general principles of reducing pressure by drainage are comprehensively addressed. Details of the mechanics of water flow in soil, rock, aggregates, geotextiles, and pipes are covered. Filtration theory and filter design are presented in a geotechnical context along with the general characteristics of drains and the assessment of their performance. Field and laboratory investigations, site instrumentation and its monitoring, groundwater computations resulting from field investigations, and various methods of slope stability analysis are discussed. The materials and construction procedures used in trench, blanket, and horizontal drains are examined in depth. Also presented is an account of granular, ferric and calcium carbonate clogging mechanisms, and maintenance procedures for controlling them. Appendices include a field test for dissolved ferrous iron and case examples. Geotechnical practitioners, students, and beginners will find this book to be a comprehensive reference for every aspect of subsurface drainage for slope stabilization. Chapters include: Groundwater, Stability, and Drainage; Flow in Granular Materials and Synthetic Fabrics; Flow in Pipes; Protective Filters; Guidelines on Groundwater and Drainage; Field Investigations; Instrumentation; Laboratory Tests; Groundwater Computations; Slope Stability Analysis; Drain Construction Materials; Points on Design and Construction; Trench Drains; Drainage of Retaining Structures; Horizontal Drains; Wells; Monitoring; Clogging; and Maintenance.