The determination of pressure-settlement performances of soils “in place ” must be the major objective in developing methods and procedures for load-bearing tests for foundations of structures and pavements. Soils in natural deposits or processed and compacted in embankments or base courses of pavements are always preconditioned and prestressed materials. Soils having different kinds of preconditioning and different levels of prestressing are in reality “new materials” with essentially different, new, and improved performances. As a consequence, there are no simple model-prototype relations between responses of soils in small-scale field tests and full-scale performances that can be used invariably without regard to the natural environmental and service conditions that control. The logical and necessary approach is to make prototype load-bearing tests on soils “in place” to yield significant pressure-settlement relations representative of these environmental and service conditions that can be translated into valid and reliable estimates of full-scale settlement performances. Practical applications of these concepts and principles of simulated performance and prototype load-bearing tests are covered. Suggestions are made for field procedures that incorporate these concepts and principles.