Abstract: A cleanroom wall panel system is provided for defining the perimeter or interior divisions of a cleanroom. The system includes a plurality of elongate retainer elements, which are mounted to wall studs, and a plurality of wall panels with hook portions configured to engage the elongate retainer elements. The retainer elements and/or wall panels may be oriented at either of two different orientations, and further are designed to accommodate some variations in the positioning of the components relative to one another, which facilitates assembly of the wall panel assembly. Each wall panel's weight is supported, either directly or indirectly, by a floor surface located below the wall panel, so that the hook portions are used primarily to secure the wall panels against the retainer elements.