Abstract: A support arm structure for the upper end of a ladder is provided and includes mounting structure for mounting one end of the support arm structure on the upper end of the ladder for swinging of the support arm structure about a transverse axis extending transversely of the associated ladder, the support arm structure being swingable in a plane in which the ladder is disposed. The outer end portion of the support arm structure includes relatively pivotable opposing jaw structures and a connecting link is connected between the jaw structures and a portion of the mounting structure stationary with the ladder whereby the connecting link may effect relative oscillation of the jaws toward and away from each other in response to swinging movement of the support arm structure relative to the ladder.