Abstract: A cord-operated control system for a venetian blind, in which a housing, attached to the head rail, holds a first drive wheel that is operatively connected to a driven bind member that rotates in opposite directions to open and close the blind with rotation of the first drive wheel in opposite directions and a second drive wheel that is operatively connected to the first drive wheel, so that the first drive wheel rotates in opposite directions with rotation of the second drive wheel in opposite directions. An endless loop operating cord is looped over the second drive wheel, so that an axial pulling force on only one of the depending portions of the operating cord on opposite sides of the second drive wheel causes the second drive wheel to rotate in one of the opposite directions. As a safety feature, a release disconnects the drive wheels from each only if there is an axial pulling force on both depending portions of the operating cord simultaneously.