Abstract: A stackable chair includes first, second, and third frame members. Each of the first and second frame members forms a front and rear chair leg joined by a seat side rail. The third frame member has opposed side portions respectively joined to the seat side rails, a transverse front nose portion, and a pair of upwardly-extending back stiles. A cushioned and upholstered seat module assembly is attached to the seat side rails. A back module assembly includes a contoured, cushioned, and upholstered back base element having a pair of channels formed therein that are configured and located so as to receive and conceal the stiles when the back module assembly is slid onto the stiles, whereby the back module assembly is attachable to the stiles along the channels. A lower lumbar support element is advantageously attached to the lower portion of the back base element.