An electrostatic clamp configured to, in use, hold an article, such as a reticle or a wafer in a lithographic apparatus. The clamp includes a lower portion; an upper portion formed of a dielectric material, and a plurality of electrodes disposed between the lower portion and the upper portion. The electrodes include a first electrode configured in use to be held at a first voltage, at least one intermediate electrode configured in use to be held at a second voltage, and a ground electrode. The at least one intermediate electrode is located between the first electrode and the ground electrode and the second voltage is between the first voltage and ground to reduce the voltage across a barrier between the electrodes and so reduce the risk of high-voltage breakdown.