Abstract: Apparatus for adjusting the height of an article, such as a table, chair or the like, includes at least one guide tube mounted in a base and a slide mounted within each guide tube connected to the article whose height is to be adjusted. The slide is locked at a selected position within the guide tube to thereby lock the article at its desired height by means of a locking mechanism which includes at least one wedge member mounted on the slide to define a space which diminishes in size between the wedge member and the guide tube and a corresponding locking member situated within the space and urged therein into engagement with the wedge member and the guide tube. Apparatus are provided for moving the locking member out of its wedged position to unlock the slide.