Orchestrating a movement towards a sensory target requires many computational processes, including a transformation between reference frames. This transformation is important because the reference frames in which sensory stimuli are encoded often differ from those of motor effectors. The posterior parietal cortex has an important role in these transformations. Recent work indicates that a significant proportion of parietal neurons in two cortical areas transforms the sensory signals that are used to guide movements into a common reference frame. This common reference frame is an eye-centred representation that is modulated by eye-, head-, body- or limb-position signals. A common reference frame might facilitate communication between different areas that are involved in coordinating the movements of different effectors. It might also be an efficient way to represent the locations of different sensory targets in the world.