Abstract: A modular wall system includes a plurality of wall panels, each with a core, a front skin, a rear skin, and at least one edging piece along at least one edge. The edging piece has first and second edgewise extensions extending first and second lengths, respectively, and defining an intermediate groove, wherein the first extension is adjacent the front skin, and wherein the first length is greater than the second length. A floor track has a base flange and a substantially vertical panel-receiving channel. At least one vertically oriented H-spline is provided for resting on the floor track and being positioned between two adjacent wall panels. The H-spline has a front flange and a rear flange joined by a web, wherein the front flange has a transverse width adapted to be received in the intermediate grooves of edging pieces of the adjacent wall panels while permitting substantially flush abutment of the front skins of the adjacent wall panels.