Out of the vast and confusing literature concerning flavor stability of beer, it is possible to pick out three factors which demonstrably favor shelf-life: low levels of in-pack oxygen, low temperature from packaging to consumption, and the presence of sulfur dioxide. Concerning the last of these, there is some questioning of whether the levels permissible in beer in the United States before a need to declare on the label (10 ppm) are sufficient to allow any protection. In this study we have ascertained the relationship between the level of SO2, the nature of the beer and its storage conditions and (a) the survival of SO2 in the product, (b) the development of staling carbonyls and (c) the development of stale character. The last of these has been judged by a properly trained panel (too often in studies of beer staling the last of these has been the weak point).