Abstract: A flanged tray and preform for making it. The preform includes a cut and scored paperboard blank having a polygonal bottom forming base panel. Each edge of the base is foldably joined to a radially outwardly extending, regular trapezoidal sidewall forming panel. The radially outermost portion of each sidewall panel carries a horizontal flange forming flap. The preform also includes a thin plastic sheet adhered to one surface of the paperboard blank. The plastic sheet covers the blank and extends over radially extending gaps between the side edges of next adjacent sidewall panels. The preform is placed in a female die with the plastic film facing upwardly. A male die presses the preform downwardly to form it into a tray having a peripheral, horizontally extending flange. The step of permanently attaching the plastic film to the paperboard blank may be carried out concurrently with the step of deforming the blank in the die.