Abstract: A roll-up type portable roadside sign of the type normally used with a resilient stand member. A novel warning flag mounting system is disclosed for such sign wherein the warning flags are retained in association with the sign such that they are collapsible with the roll-up sign cross members and remain attached thereto. Such mounting is achieved by pivotably attaching the warning flag poles to the substantially vertical cross member of the sign. A rotatable support bracket is also attached to the cross member and includes a pair of spaced curled ends which receive the warning flag poles such that they extend substantially upward and are disengageable therefrom in order to permit collapsing of the sign assembly. The support bracket is rotatable such that it assumes a position substantially collinear with the remainder of the sign components, enabling the entire assembly to be quickly and conveniently stored.