Abstract: A back brace for sitting is disclosed, having a frame with a back portion hingedly coupled to a seat portion, and a support mechanism coupled to the back portion and able to expand and contract the back portion, changing the distance between the top end of the back portion and the hinge. The brace also includes shoulder straps coupled to the back portion of the frame, looping under a user's arms, as well as an abdominal strap coupled to the back portion and configured to encircle the user. The brace also comprises a seat cushion coupled to the seat portion of the frame. The support mechanism reduces the force exerted on the user's back by supporting the user with the back portion of the frame and driving an upper portion of the user's back away from a lower portion of the user's back.