Abstract: The invention relates to an additive manufacturing apparatus which includes a platform guiding arrangement 10 having a build platform 12 and a mounting arrangement 14 comprising guiding elements 16, 18 mounted to the build platform 12. The mounting arrangement 14 is configured to permit displacement of the build platform 12 in a vertical or Z direction whilst permitting unconstrained thermal expansion and contraction of the build platform in the horizontal or X-Y plane. The guide elements 16, 18 abut against adjacent sides of the build platform 12 to inhibit angular displacement about a vertical axis and permit unconstrained thermal expansion and contraction in the X-Y plane.