Shells from marine, estuarine, freshwater, and land molluscs are well preserved in calcareous archaeological deposits and naturally accumulating sediments. By sampling such deposits and sediments the shells can be recovered and identified to species to reveal a great deal of information about economy and environment. In the case of shell middens, the molluscs mainly accumulate as a result of human discard patterns and thus mainly relate to the economy and eating habits of the community responsible. Other situations, for example buried soils, ditch and pit fills, slopewash deposits, blown sand and loess, old water courses, and alluvium, are important for their environmental evidence because most species prefer to live in particular habitats and rarely move far from home. A typical sample for analysis comprises 1 kg of sediment wet‐sieved using a 0.5 mm mesh. Land Mollusca species can be broadly subdivided into: shade‐loving woodland species; open‐country grassland, arable, and scree‐loving species; catholic species capable of living in a wide range of habitats; and marshland species who live in damp marshy conditions. Freshwater Mollusca can be divided into: slum species that live in small bodies of water, poorly aerated and subject to periodic drying; catholic species found in almost all freshwater contexts; ditch species that prefer plant‐rich slow streams; and moving‐water species that prefer large bodies of well‐oxygenated water. Where accumulating sediments are available it is possible to take samples from different horizons and thus chart changes in local environment through time.