An adjustable anchor for anchoring a lift cord in a movable rail of a covering for an architectural opening includes a housing which is releasably positionable interiorly of the movable rail in alignment with a lift cord for the covering with the anchor including a rotatable drum within the housing and around which the lift cord can be wrapped or unwrapped by rotating movement of the drum with a tool. Two distinct systems are provided for releasably securing the drum in any selected position to retain the amount of lift cord wrapped therearound with the two system acting in mutually perpendicular planes for reliable anchoring of the lift cord.