Abstract: An articulated robot arm or the like comprising a base, an upper arm which is pivotally secured to the base at a shoulder joint, a lower arm pivotally secured to the upper arm at an elbow joint, and optionally a "hand" or tool support pivotally secured to the lower arm at a wrist joint. A parallelogram linkage controls the relative position of the upper arm, lower arm, and base. The linkage has first, second, third, and fourth links joined by pivots. The first link is a crank which is pivotally connected to the base by a first pivot which is coaxial with the shoulder pivot. The second link of the parallelogram linkage is parallel to the crank link, and is fixed with respect to the lower arm. The third and fourth links join the first and second links to complete the parallelogram. At least one of the third and fourth links is fixed to the upper arm.