Landfill gas is the end product of the degradation of biodegradable wastes in a landfill site. Proper management is essential because of the risk of fire and explosion in nearby buildings and also to reduce the risk of asphyxiation. This paper maintains the precautionary approach of the first edition as many aspects of landfill management are still under development. It describes gas formation, composition and migration along with methods of assessing, monitoring and control. The book concludes with information on the options available for its management.