Practical experience has generally been the source of guidance for seed storage from one season to the next. Our ancestors soon realized that avoiding moist warm conditions and protecting seeds from predators was necessary if seeds were to survive till the next planting season. Simple experiments, using different combinations of temperature and seed moisture content and/or relative humidity, showed that much longer storage periods could be attained by lowering one or both of these factors. Drying seeds and storing them in air-tight containers, or even under vacuum, at subambient temperatures could produce longevities of years or even decades. Many myths were recorded in the popular literature about longevities of centuries or even millennia. Recent research on the biochemistry and biophysics of deterioration have led to new theories on longevity that have turned our thinking upside down. A discussion of both practicalities of storage and theoretical aspects will be presented. Simplified recommendations are proposed for determining the most cost-effective approach for seed storage under various environmental and economic conditions.