Arbitrating circuitry arbitrates between a plurality of inputs and a selection of at least one of said plurality of inputs. The arbitrating circuitry includes an array of interconnected arbiter devices operating with respect to a set of Q inputs. The array comprises M sub-levels with at least a first sub-level having T arbiter devices each operating with respect to U inputs, where Q=UM and Q=TU. For each sub-level other than a first sub-level, each arbiter device in a sub-level receives as input requests signals indicating an arbitration outcome for two or more arbiter devices in a preceding sub-level and arbitrates between those input requests.