There are still quite a few unsolved mysteries in physics, ranging from the accelerated expansion of the Universe to the asymmetry between matter and antimatter. The proposed answer most probably lies in a physics beyond the Standard Model in a so called Dark Sector which is populated by axions, WISPs and WIMPs. Their nature and properties is still a mystery in particle physics. Research is presently gathering increasing momentum and attracting the efforts of scientists from many international institutions and collaborations. The "18th Patras Workshop on Axions WIMPs and WISPs” is the latest event in an annual series of conferences, started in 2005 at CERN. This workshop is aiming to continue the rich and successful series, reviewing recent theoretical advances, laboratory experiments, novel ideas as well as astrophysical and cosmological results in the field. Participation by young scientists is strongly encouraged.