The activity of mound‐building ants results in the production of a pedon which is profoundly different from its uninhabited counterpart in structure, composition, behavior, genesis, and pedogenic regime. The formicarious pedon is offered as a theoretical construct to organize the body of knowledge regarding the effects of ants on soils and to represent the initial effects of mound‐building ants on soils. Formicarious pedons are characterized by a large mound overlying the original pedon. This mound often has a crusted or mulched exterior and a highly porous interior. The interior of the mound, as well as the soil below the mound is riddled with channels and chambers created by the ants. The mound consists of surface and subsoil material and differs from the surrounding soil in texture, structure, and chemistry. This leads to a different pedogenetic environment. The process of mound‐nest construction is the dominant soil‐forming process operating within the formicarious pedon. As colonies relocate through time, the effects of the ants can be applied to entire landscapes.