This paper investigates the degree to which glass bottled milk is an environmentally friendly alternative. A recent life cycle assessment for fluid milk packaging alternatives is utilized to quantify the environmental costs associated with each packaging type. We conduct a sensitivity analysis to identify the return and reuse rates under which the glass bottle has a lower environmental impact than the alternatives. With eight reuses and 95 percent return rate, glass bottled milk has a lower environmental cost than the alternatives. Twelve reuses and a 100 percent return rate is necessary for glass packaging to have the lowest social cost.