This guide is intended to aid in the proper selection and application of PC overlays for structures in the transportation industry@ focusing primarily on bridge and parking garage decks. Materials discussed are epoxies@ polyesters@ and methacrylates for application on either concrete or steel surfaces. In general@ these overlays are used for the protection of the substrate and are designed to be compatible without causing stress. The low permeability of PC overlays makes them resistant to the penetration of water and provides protection against chloride penetration. Overlays are designed to minimize deterioration from repeated thermal expansion and contraction (Fowler et al. 2001). In addition to describing the characteristics of PC overlays@ this guide includes chapters on surface preparation@ application@ quality control@ and handling and safety. The information should allow the reader to select materials for a given application and may serve as the basis for the preparation of overlay specifications.