Soil reinforcement is a practical solution to construction over weak soils. Application of the kinematic approach of limit analysis to reinforced soil is reviewed, both for traditional reinforcement with strips or sheets of geosynthetic material and for fiber-reinforced soils. The development of the failure criteria for isotropic and anisotropic fiber composites is presented. The kinematic approach is applied to evaluating limit loads on reinforced foundation soils. Patterns of reinforced soil failure determined in earlier laboratory tests are utilized. A method for practical calculations of the bearing capacity is presented, and the depth of placement of the geosynthetic layers is recommended. The method is extended to two-layer foundation soils with the upper layer reinforced either with geogrids or fibers, or with both. Preliminary results indicate that fiber reinforcement can be as effective as geogrids. Application of this concept is envisioned in construction of unpaved roads, temporary aircraft parking facilities, or when placing footings over weak soils. Foundation soils with combined reinforcement include layers of geogrid placed in the fiber-reinforced fill, to produce a slab capable of carrying large loads. To analyze the limit state of the slab, a model of fiber-reinforced soil was used first to determine the properties of the fiber-reinforced fill. The contribution of the geogrid to the strength of the slab was then determined by considering two possible modes of failure: slip and tensile rupture. The framework of the kinematic approach of limit analysis was used to arrive at the limit loads on reinforced slabs.