A lithography apparatus and device manufacturing methods are disclosed. A lithography apparatus includes a support stage (16), and a measurement system (12-14) including a sensor part (13) and a reference part (12, 14), the measurement system being configured to determine the position and/or orientation of the support stage (16), or of a component mounted on the support stage, relative to a reference frame (6, 8, 10) by using the sensor part (13) to interact with the reference part (12, 14), wherein: the reference frame (6, 8, 10) comprises N sub-frames (6, 8) coupled together so as to behave predominantly as a single rigid body with respect to vibrations below a first reference frequency and predominantly as an N-body system with respect to vibrations above a second reference frequency, where N is an integer greater than 1.