This special issue of Planetary and Space Science on “Scientific Preparations for Lunar Exploration” is comprised of papers presented at a workshop of the same name, which was hosted at ESA ESTEC in Noordwijk, the Netherlands on the 6th and 7th February 2012. This workshop was attended by around 180 scientists from a large spectrum of scientific disciplines, including space and planetary sciences, astronomy, physical sciences, life sciences, medicine and human physiology. The goal of this workshop was to identify and highlight the major scientific unknowns surrounding future exploration activities on the Moon and to identify the scientific work that needs to be performed to enable the exploration activities of the future.