Abstract: In a preferred embodiment, a mounting bracket for support of a window air conditioner on a window sill installed in a window opening in a wall of a building, the bracket including: a generally horizontal support member for supporting a portion of the window air conditioner extending outside of the building, a proximal end of the generally horizontal support member being for attachment to the window sill; a foot member to rest against an outside surface of the wall below the window opening; a strut member having an upper end thereof attached to an attachment point near a distal end of the generally horizontal support member and a lower end thereof attached to the foot member; and apparatus to selectively adjust height of the proximal end of the generally horizontal support member above the window sill, depending on construction of the window sill and obstacles in the window.