The invention relates to a prosthetic socket for a residual limb of the lower extremity or upper extremity of an individual person. The residual limb has particular dimensions and anatomical contours; the prosthetic socket has dimensions and contours that fit the dimensions and contours of the residual limb. The prosthetic socket may also fit in a manner that is biomechanically particularly appropriate for the individual. The prosthetic socket is an assembly of components from groups of components that include (a) struts arranged longitudinally with respect to the residual limb, (b) proximal brim members arranged proximally to the struts and connected thereto; and (c) distal socket members disposed at the distal base of the prosthetic socket. The socket components within these groups may be modular in that they can vary with respect to dimensions and/or contours, and yet have common connecting features that permit assembly of the components together to form the prosthetic socket.