Abstract: A ladder extension is disclosed comprising two separable sections to be coupled together in longitudinally overlapping relation by first coupling means coupling a portion of a first ladder section proximate one end thereof to the second section so as to permit the first ladder section to be rotated with respect to the second ladder section to a position where second coupling means are aligned in position for engagement, preferably with stop means being provided to stop rotation of the first ladder section at a position where the second coupling means are aligned for engagement. The ladder comprises two separable sections which is easy to asemble by a single person even under adverse field conditions and which provides means to positively lock together the sections when assembled into an extension ladder.