This 4th edition updates the latest research on earthworms. More than 3,000 species of earthworm exist in the world. They are considered to be an important ally in advancing environmental and biomedical research. Earthworms play an important role in forest or agricultural ecosystems and play an increasing role in biomedical issues. Earthworms are critical to the environment because they consume huge quantities of decomposed litter, manure, and other organic matter deposited on soil - helping to convert it into rich topsoil. Earthworms can also help reduce soil compaction, improve permeability - thus providing channels for root growth, water infiltration, and gas exchange. Earthworms are also important animals for the assessment of the toxicity of chemicals, such as herbicides and pesticides, which are deliberately released into the environment. Earthworms are superb 'barometers' or 'sentinels' providing an early warning of deterioration in soil quality.

Clive A. Edwards was appointed as Chair of the Department of Entomology at the Ohio State University in 1985. He has published extensively on soil ecology, environmental toxicology, and sustainable agriculture, and he is currently recognized as a world authority on earthworms. His book is the first comprehensive book on earthworms since Charles Darwin's The Production of Vegetable Mould through the Action of Earthworms which was published in 1881. In 1996, Professor Edwards's book Ecology of Earthworms won a Presidential Citation from the U.S. Soil & Water Conservation Society. A prolific writer, he has published 378 scientific papers including writing, editing or co-editing 30 books.

Paul Hendrix is a faculty member of the Conservation Ecology Program at University of Georgia, Center for Biological Diversity and Ecosystem Processes. His current NSF funded research projects focus on exotic earthworm invasion in wildland ecosystems. He has published extensively on the subjects of earthworm management, ecology, soil ecology. His publishing record features 5 books that are author/co-authored, 20 chapter contributions to edited volumes, and 78 journal articles.

Norman Arancon obtained M.S. and Ph.D. degrees in Environmental Science from The Ohio State University (OSU), Columbus, Ohio USA after an award from Fulbright and The Ohio State University in 1997 to 2001. Together with Dr. Clive Edwards and his students at the Soil Ecology Laboratory, they pioneered research on vermicompost applications in the field using other commercially important vegetables to investigate their effects on chemical and biochemical changes in soils.