The outer side of a slide-out floor (20) is supported by the outer end of an inner rail member (40). The inner rail member (40), or at least a support wall thereof, is telescopically angled within an outer rail member (32) such that the angle increases as the inner rail member (40) is extended, so as to position the outer end of the slide-out floor (20) at an elevation that is substantially flush with the fixed floor (74) when the slide-out floor (20) is fully extended.