This volume contains the proceedings of the 5th International Symposium on Symmetries in Subatomic Physics (SSP2012), that was held in Groningen, The Netherlands from  18 till 22 June 2012. This sequence of symposia is now firmly connected with one of the main branches in fundamental nuclear and particle physics, i.e. in searches for physics beyond the Standard Model, focused on the (violation of) the discrete symmetries of Parity, Charge conjugation and Time reversal invariance. This field comes in various disguises: With large experimental facilities and large collaborations, as in LHC physics or in neutrino experiments, but also as table top experiments by small groups in the field of nuclear, atomic and molecular physics, such as in searches for a permanent electric dipole moments and atomic parity violation.
Bringing the practitioners of these divergent fields together gives a coherent overview and see the complementarities of  the various approaches to the same question: why is the Standard Model what it is and what lies beyond it.