A chair includes a base, a seat operably supported on the base for depth adjustment, and a back operably supported by an upright that extends from the base for recline. The back includes a structural back support, a rear cover covering a rear side of the back support, and a front/lower concave cover covering the upright between a rear of the seat and below the back support to provide a one-piece back and seat appearance. The concave cover defines a concavity shaped to receive a rear of the seat to facilitate depth adjustment, but so that the one-piece back and seat appearance is maintained. The concave cover further includes upwardly extending tabs that engage a lower marginal edge of the back support to facilitate assembly. A flexible sheet covers a front side of the back, and includes a lower portion that wraps around the lower marginal edge and onto a rear surface of the back support, and the concave cover includes an upwardly facing flange that overlaps the lower marginal edge of the back support to trap the lower portion against the lower marginal edge. A vertically adjustable lumbar support is operably mounted on the back support for vertical movement, and handles are provided that move along vertical side edges of the back along a path that is non-parallel the vertical path of the lumbar support.