An adjustable chair having a back rest and a contour adjusting mechanism for adjusting the contour of the occupant engaging surface of the back rest. The contour adjustment mechanism comprises a series of longitudinally spaced adjustment linkages which also form part of the back rest. The contour adjustment includes adjustments for at least spinal curvature of an individual. For this purpose a gauge may be provided for pre-calculating the individual's back curvature, and this pre-calculation used in conjunction with the adjustment mechanisms to effect the desired adjustment of the occupant engaging surface.
