A boat slip step assembly (10) for being mounted proximate the corner of a boat slip (16). The step assembly (10) includes at least one tread member (24) for being mounted in a corner of the boat slip (16) below the level of the upper surface of the boat dock (14) that defines the boat slip (16). The tread member (24) has a first edge portion (26) for being secured to a first dock section (20), and a second edge portion (28) for being secured to a second dock section (22).