The research development in this review is divided into successive periods: (1) "From Darwin to Satchell", covering the "pre-experimental" decades cleating with the functions of earthworms, (2) "Litterbag Studies", characterized by field experiments on the faunal, influence on titter decomposition, (3) "The Time of IBP", concentrating on community energetics, (4) "The Microcosm Era", laboratory studies that started with simple systems, followed by increasing complexity of experimental setup and community of organisms, including living plants, and ending to laboratory-scale "ecosystems", (5) the recent "Biodiversity Boom", analysing the relations between soil biodiversity and ecosystem functions, and (6) the current "Holistic View" that tends to link the diversity and functions of aboveground and belowground communities. These "periods" started roughly in this order, but are largely overlapping, since the early techniques are in continuing use together with the modern ones. The current knowtedge on the role of soil biota, their diversity and various components has accumulated mainly during the last 30 years, resulting in the modern view of soil fauna as a part of the ecosystem. (c) 2006 Elsevier GmbH. All rights reserved.