While symmetries are well understood for Boolean formulas and successfully exploited in practical SAT solving, less is known about symmetries in quantified Boolean formulas (QBF). There are some works introducing adaptions of propositional symmetry breaking techniques, with a theory covering only very specific parts of QBF symmetries. We present a general framework that gives a concise characterization of symmetries of QBF. Our framework naturally incorporates the duality of universal and existential symmetries resulting in a general basis for QBF symmetry breaking.Symmetry breaking for QBF has already been studied more than ten years ago [5,6,7], and it can have a dramatic effect on the performance of QBF solvers. As an extreme example, the instances of the KBKF benchmark set [8] are highly symmetric. For some problem sizes n, we applied the two configurations QRes (standard Q-resolution) and LD (long-distance resolution) of the solver DepQBF [9] to this benchmark set. For LD ⋆