Abstract: A vehicle having a slide-out room section includes an operating mechanism for moving the slide-out room section laterally relative to the stationary room section for expanding the interior volume of the vehicle. The slide-out room section has an outer end which is mounted via a vertically movable connection arrangement to the operating mechanism, and a cooperative support arrangement is provided for the inner end of the slide-out room section to enable the slide-out room section to be vertically dropped when fully extended to place the slide-out room section floor flush with the floor of the stationary room section. The vertically movable connection arrangement includes a support member interconnected with the extension member and movable therewith, and a mounting member secured to the movable room section and engaged with the support member.