An adjustable-width barricade for removable installation at the bottom of a staircase includes a flexible, frameless, planar, and generally-rectangular barrier member that extends between two posts on either side of the staircase. The barrier member is installed in a banister-to-banister configuration, a wall-to-banister configuration, or a wall-to-wall configuration. The barrier member has a front and back surface that forms an interior space therebetween. The adjustable-width barricade further includes a plurality of fasteners extending from one or both sides of the barrier member for tensioning engagement between one or both posts that maintains the lateral or horizontal integrity of the barricade. A plurality of rigid, structural support members are removably insertable in vertical channels within the interior space of the barrier member to provide vertical structural support when the barricade is installed across the bottom of the staircase or, alternatively, when the barricade in in a rolled-up stowed configuration.