Right and left hand casement windows employ a simple and compact operating linkage which can be installed either to the right or to the left of a center mounted gear drive, thus accomplishing universal operation of left or right hand windows through a structurally identical linkage. Locking tabs provided on an operator link of the mechanism coact in right or left hand mode of operation with locking projections on a stabilizer link to assure positive and secure closing of the window even in cases where the primary jamb-mounted window sash latch is unfastened.