A technique adapted from the aid-climbing methods practiced by rock climbers is described for climbing tall trees. Equipment lists are provided and the technique is illustrated. The technique provides an alternative to climbing with spikes or shooting or throwing a line from the ground over a limb high above. It is simple and easy to learn and, once practiced, can serve as an efficient and safe method to access the canopy of a large tree. The technique is applicable to trunks up to ~ 1.5 m diameter, or to heavy lianas growing on even larger trunks. This method can be used not only to gain access to nearly any large tree, but also provides one with the ability to move about in that tree with relative ease and safety. With practice, a clumber using this method can ascendd from ground level to 30-40 m up in the forest canopy in one hour or less. The advantages over other tree-climbing methods are discussed.