A stair-adjustable crutch characterized by an adjusting cuff having a cone with an elongated or extended, flared and offset lip and lip receptacle provided in the crutch foot to facilitate selective angular adjustment of the crutch foot and frame from an aligned configuration. This adjustment is effected by manipulation of a rod fitted with a pair of spaced-apart, wishbone-shaped legs extending into the cone, which legs are provided with shaped tabs or locks for selectively entering and exiting spaced-apart sets of vertical and angled slots in the cone of the adjusting cuff. Up and down movement of the adjusting rod facilitates both selective conventional operation of the crutch with the crutch foot in linear alignment, and angling of the crutch frame and upper crutch foot at the adjusting cuff with respect to the crutch foot below the adjusting cuff, to adjust the user's weight and more safely ascend and descend steps and stairs. A method for angularly adjusting a crutch frame and upper crutch foot with respect to the lower crutch foot by providing an adjusting cuff having a cone with an elongated, flared lip and lip receptacle in the crutch foot and a rod and lock mechanism that interacts with the adjusting cuff to facilitate more safely climbing and descending steps and stairs.