A levelling stabilizer for a ladder and the like comprising a transverse brace (1) adapted for bridging the bottom stiles (2) of said ladder, two leg portions (3) pivotally fitted to said brace and an adjustment arm (7) acting between said brace and said leg portions to allow each said leg portion to be independently moved between a first fully retracted position aligned longitudinally with its respective stile and a second fully extended position at an angle normal to said stile.