Abstract: The present invention describes a workholding apparatus for holding workpieces that are to undergo various machining processes. The workholder apparatus is particularly suitable for numerically controlled machining applications. The workholder consists of a main body having a generally flat work surface and two or more clamping assemblies slidably located beneath the work surface. The invention includes a means for accurately and repeatably clamping a workpiece to the work surface, so that a part may be removed at an intermediate stage for examination or other processing, and returned to the workholder in the same location. A major advantage of the present invention is the clamping is accomplished without producing undesirable stresses in the workpiece, and all sides of the workpiece can be exposed for machining without changing the attachment of the workpiece in the workholder. A modular and extensible embodiment of the invention is also described.