Gypsiferous parent materials are uncommon in Europe, and gypsum is generally a minor constituent or absent in these soils.  Some semiarid areas of Spain are exceptions and their environment is similar to some areas of North Africa and the Southwestern United States.  Dryland agriculture is unfeasible or marginal on these soils, mainly due to their low water-holding capacity. These circumstances, plus the traditional line of reasoning in soil science related to silicate clays, hinder our understanding of the morphology, genesis, and behavior of soils having significant gypsum content. A primary challenge is to obtain general acceptation of the existence of gypseous soils, i. e., soils where gypsum is the most abundant component, or where gypsum is responsible for the key properties of the soil. Soil scientists have to be trained to recognize gypseous soils in the field for mapping and interpretive purposes. A second challenge is to apply and improve our knowledge of physical and chemical properties of gypsum and to establish the size, shape, and arrangement of the gypsum particles in the different diagnostic horizons. This will be seminal for understanding the genesis and properties of Gypsids, interaction between water and gypsum particles, influence of soil moisture on mechanical properties, rooting capability, response to various land uses (i.e., urban and irrigated agriculture), and the hosting capability for wildlife and endemisms.  Finally, the intrinsic value of gypseous soils in terms of pedodiversity should be considered.