Environmental biotechnology, which was in its infancy in the early 80's, has evolved thanks to the revolution brought about by molecular biology. Multiple successes in the biological cleanup of civil and industrial wastewater and of hydrocarbon soil pollution, demonstrate the vast power of clean technologies. In addition, the buildup of information on the activities of microorganisms as catalysts in all sorts of natural, industrial and animal environments has flourished. There is a continuing realization of the critical role of microbial processes in biological, industrial and geological systems. Since environmental biotechnology has matured, it is ready to tackle bigger challenges: the scaling up of many bioremediation systems still in progress, the search for novel biocatalysts for industrial applications, the continuing effort against common human life-threatening processes such as antibiotic resistance, the accumulation of hormone-mimicking substances (endocrine disrupters), the deposition of air-borne pesticides in the environment and, the degradation of recalcitrant contaminants. These endeavors will help prevent the contamination of food chains, protect human life and allow for human activity and economic development that do not compromise environmental sustainabijity. This volume includes the key lectures and participants' contributions delivered at the NATO-funded Advanced Research Workshop (NATO- ARW No. 980838) Bioremediation of Soils Contaminated with Aromatic Compounds: Effects of Rhizosphere, Bioavailability, Gene Regulation and st rd Stress Adaptation, held in Tartu, Estonia, from the 1 to the 3 of July 2004, and attended by participants from 15 countries.