The increasing use of geotextile-reinforced soil systems for important earth structures requires proper understanding of their behavior and validation of the assumptions in their design. Geotextile reinforcement materials are particularly useful in reinforced soil systems built using indigenous backfill soils, which may be finer grained, more plastic and less permeable than fin materials commonly specified in soil reinforcement practice. Four aspects of the performance of geotextile-reinforced soil structures were investigated by performing: (I) An evaluation study of the suitability of poorly draining soils for reinforced soil structures; (2) a finite element study on the deformability and design aspects of geotextile-reinforced soil walls; (3) a centrifuge study on the failure mechanisms and on the suitability of limit equilibrium methods to predict failure of geotextile-reinforced soil slopes; and (4) a field instrumentation study to evaluate the performance of a permanent geotextile-reinforced slope built using decomposed granite as backfill material. Each analysis provides specific lessons useful for understanding the performance of the engineered composite material which is reinforced soil. Collectively, they illustrate that the behavior of reinforced soil structures (and probably of earth structures in general) may defy characterization by a single method of analysis. Instead, by complementing facets in the performance of a geotechnical structure can be achieved.