The Mississippi Department of Transportation has used hydrated lime for more than 30 years to stabilize subgrades. In 1998, a project was initiated to assess material properties and performance derived from lime-treated subgrades. Some pertinent findings of the study are described. In situ properties of lime-stabilized subgrades were identified based on falling weight deflectometer deflection measurements, ground penetration radar profiles, and dynamic cone penetrometer logs. The in situ properties were compared with laboratory strength and resilient modulus test results for the same materials to establish reliable design-resilient and strength properties for these stabilized layers. A laboratory mixture design and testing protocol was developed for lime-stabilized subgrades. A comparison of field test data and laboratory test data showed that laboratory design test properties were achieved in the field. These properties were used in a mechanistic analysis to assess the effectiveness of the lime-stabilized subgrades in Mississippi. The lime-treated subgrade layers in the four pavements evaluated proved to be effective structural layers.