Shale gas is natural gas – mainly methane – trapped within the micropores of shale formations or adsorbed onto the shale (sedimentary rock). In Europe, known deposits exist in the UK, France, the Netherlands, Germany, Poland, the Baltic States and Scandinavia. In Switzerland, deposits are suspected to lie in the Permo-Carboniferous trough of Northeastern Switzerland, below Lake Geneva, and in Lower and Middle Jurassic strata, e.g. in Canton Fribourg. In view of the depletion of conventional energy resources and as a result of advances in drilling technology, the exploitation of shale gas reserves – long considered unviable – now appears to be economically attractive. In Switzerland and in Southern Germany, debates have been prompted by the awarding of concessions north of Lake Constance and the suspension of drilling licences in Canton Fribourg. This factsheet is intended to provide an overview of the current state of scientific knowledge in this area.