Foundations and other structures may be subjected to uplift forces under special circumstances. For those foundations, during the design process it is desirable to apply a sufficient factor of safety against failure by uplift. During the last 40 or so years, several theories have been developed to estimate the ultimate uplift capacity of foundations embedded in sand and clay soils, and some of those theories are detailed in this chapter. The chapter is divided into two major parts: foundations in granular soil and foundations in saturated clay soil (f = 0).