Abstract: An adjustable seating apparatus with full torso support for supporting persons of varying sizes. The seating apparatus is portable and adjustments can be made without the use of tools. A base unit includes a number of detachable elongated members which can be replaced with different size members, permitting both the length and width of the support apparatus to be adjusted. A backrest is supported by vertical members which are also detachable to permit adjustments in the height of the backrest. The backrest also includes a restraint for securing the user to the backrest about the torso. An optional tray is also adjustable in height and provides a work surface for the user.