Soil science stands on concepts arising from the experience in temperate-humid countries, where geology and climate explain that gypsum in soils, if present, occurs as a minor component, in the so-called gypsiferous soils. Parent material, geomorphology and climate in some dry areas around the world, can result in soils or horizons where gypsum is the most abundant component, the gypseous soils. From the 1950's Soil Taxonomy provides diagnostic horizons related to gypsum content; criteria and definitions have evolved, and now a set of categories for classifying this kind of soils is available. However, the properties and behavior in the field have not been fully studied for gypseous soils or horizons, some of them containing more than 90% gypsum. Their weak knowledge leads to a forced or simplistic application of classic concepts and methods of soil science that can be unsuited, unsound or impractical for gypseous soils. We discuss some concepts needing careful consideration or study such as illuviation, secondary visible gypsum, cementation or induration, binding forces between gypsum crystals. We also stress some flaws in the analytical procedures occurring more often than desirable, as is the case of laboratory drying temperature, granulometry methods based on Stokes law, errors in gypsum content determination, errors in water holding determination, lack of adequate chips in tables for field color description. Changes in consistency or other properties due to water content and to sun heating, and long-term volume increase are easily observed in the field, these features need to be taken in to account to understand gypseous soils behavior and genesis. We propose to abandon the clay-centric line of reasoning when passing from gypsiferous to gypseous. This is not heterodox in soil science, where litter, peat or other non-mineral formations were early accepted as soil materials.