Abstract: An improved anchor socket and jig assembly for holding implements in concrete is provided which facilitates assembly of the socket element on the base member of the jig assembly and which affords substantially expanded adaptability of the jig for varied size implements and avoids the need for bolts or other extraneous means to secure the socket member to the rail member.The improved jig assembly comprises a longitudinal base member preferably of substantially rigid plastic composition which is provided with locator openings which fit one of the feet of the socket member and, cooperating therewith, a mating turn slot. Both the openings and the turn slots are formed to accommodate the feet of the socket member. The assembly of the socket in the base member in a secure position is readily effected by positioning the socket member between the rails of the base member and locking the two by a manual quarter turn rotation of the socket member in the base member.