a molded plastic closure for a beverage container , the closure having a shell with a top panel and a depending skirt , the shell being molded in one piece from a hard thermoplastic material . the closure is provided with an annular flange which extends from the underside of the top panel and which forms an annular space with the inside of the skirt . a liner is formed in situ within the closure by compression molding from a compression moldable soft , rubbery thermoplastic material , the underside of the top panel and the inside of the annular flange serving as molding surfaces . the annular flange is supported against lateral loads by a series of ribs which extend between the annular flange and the depending skirt . the liner is interlocked with the annular flange by interengaging ribs and recesses . both a top seal only closure for non - pressurized beverages and a top and side seal closure for pressurized beverages are disclosed .