Integrated monitoring is now defined as the repeated measurement of a range of environmental variables in a number of environmental compartments, such as water, soil, plants and animals (see page 2 of Document 1 for definition). It is a concept which is motivating international cooperative monitoring ventures and which may prove key in understanding and controlling the effect of pollutants on the environment. GEMS feels it is important at this stage to make a compendium of the latest thinking on integrated monitoring, in order to provide under one cover the basis for future development of the concept and its associated methodologies.