A special issue of the International Journal of Environmental Analytical Chemistry contains selected papers presented at the workshop on sequential Extraction in Sediments and Soils held in Sitges, Spain, on 29 March-1 April 1992. The event was organized by the Community Bureau of Reference (BCR), which embodies the Community's specific programme of research and technological development in the field of measurement and testing (BCR 5, 1990-1994) and the Department of Analytical Chemistry of the University of Barcelona, in collaboration with the Comissio Interdepartamental de Recerca i Innovacio Tecnologica and the Department de Medi Ambient de la Generalitat de Catalunya. The determination of extractable trace metal contents in soils and sediments is currently performed in many laboratories. Single and sequential extraction schemes are used for the assessment of different "forms" of trace metals. However, the lack of uniformity in the different extraction procedures used does not allow the results to be compared worldwide or for the procedures to be validated. Indeed, the results obtained are highly dependent on the extraction procedures followed. Owing to the need to establish common schemes for single and sequential extractions as well as for the improvement of the quality of extractable trace metal determination in soils and sediments, the Community Bureau of Reference organized a project of which the first step was to adopt common procedures after consultation with European experts and to test these procedures in interlaboratory exercises. A workshop was organized for all the project participants in order to discuss the results obtained at this stage. It aimed to establish the state of the art of extractable trace metal determinations, and to define the use applicability and necessity of the determination of forms of metals, to investigate where limitations exist and to discuss the work necessary to overcome these. 52 participants from 13 European countries attended the workshop's lectures, round table discussions and plenary sessions. Some 23 selected papers are brought together in the present 230-page issue of the Journal, giving specific practical examples of extraction analysis and highlighting the strong need for the use of well defined and validated extraction processes.