The aim of the project has been to record the Biodiversity of the invertebrate ground fauna in the Ogof Ffynnon Ddu Nature Reserve in the Swansea Valley. Fieldwork was carried out during 2006 through a series of site visits from April to September. The samples have since been sorted and the identified to species level as far as possible. Particular attention has been given to the spiders, beetles and springtails. This is the first detailed study on the invertebrate biology of the site and the results will form part of the management plan being compiled for the reserve.