An interior wall system formed from two opposing walls. Each opposing wall is assembled from a plurality of composite wall panels, each wall panel having an exterior surface material and an interior layer of insulating material bonded to one side of the exterior surface material. Each opposing wall is anchored to top and bottom U-shaped support members and adjoining wall panels of each wall are connected by a plurality of retaining clips. The retaining clips may be adjusted in length to accommodate various widths between the opposing walls. Additionally, splines are inserted between the first and second walls along the seams between adjoining wall panels. The wall system also includes a door frame comprising first and second jamb members and a lintel member, each having a spacing member attached to approximately the center thereof. The spacing members are inserted between the opposing walls and are used to anchor the door frame in place.