The invention relates to a lithographic apparatus including an illumination system configured to condition a radiation beam, a patterning device support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate support constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and an encoder-type measurement system configured to at least during projection of the patterned radiation beam onto a target portion of the substrate continuously determine a position quantity of a patterning device supported on the patterning device support using a grid or grating provided on the patterning device.