This document has been prepared as part of the regular programme activities of the FAO Marine Resources Service, Fishery Resources Division, aimed at promoting improved practices for the assessment and management of fisheries through the production of background documents, technical guidelines and handbooks. In several parts of the world, the productivity of natural populations of marine invertebrates have come under excessive pressure, as rising demand and prices for these generally high-value species lead to their overexploitation. Environmental changes to nearshore environments due to other human activities have on occasions contributed to damaging nearshore stock productivity further. A partial solution has been to enhance or restore populations of nearshore areas, using techniques that range from those resembling extensive aquaculture, to the scientific management of stocks as used for finfish populations. This document reviews the scientific knowledge derived from enhancement activities in shellfish and other invertebrate populations, and attempts to extend the concept of "enhancement" to include any activity which increases the productivity of a marine resource, whether this is by controlled harvesting, stock additions or habitat/environmental manipulation. Multidisciplinary guidelines and operational criteria for conducting and assessing invertebrate stock management programmes are also provided.