The history and development of the seed quality curve is reviewed. Germination data obtained with the 65 F test are used to show how to position a lot of planting seed on the curve. The seed position on the curve determines the equivalent exposure units (EEU s) to 100% relative humidity and 50 C. Performance data are given that show the expectations of seed lots having different EEU s when planted under controlled cold conditions and under natural field wet-cold conditions. The results show how resistance of seed and seedlings to wet-cold conditions decrease as EEU s increase from 0 to 6. Seed coats increasingly support mold growth as EEU s increase from 0 to 6. Final field stands are negatively correlated with 65 F germination and damping-off as EEU s increase from 0 to 2.5. With EEU s of 2.5 to 6, final field stands are positively associated with germination. Other associations of EEU s with seed and seedling performance are given.