The purpose of this book is to review and assess our current understanding of invertebrates in terrestrial and terrestrially-dominated (i.e. lower-order stream) ecosystems. It emphasises the centrality of the activity of invertebrates, which influence ecosystem function far out of proportion to their physical mass in a wide range of situations, particularly at the interface between land and air (litter/soil), water and land (sediments) and in tree canopies and root/soil systems. Consisting of 16 chapters by authors from the USA, Canada, Europe and Australia, the book is essential reading for ecologists and invertebrate biologists.