More than 40% of the bridges in the United States need repair, strengthening, or replacement. Because of limited funds, many states are forced to post load restrictions on their bridges as a temporary measure. Recently, fiber-reinforced polymers (FRPs) have emerged as a practical solution for repair or strengthening of highway bridges. Since there are no nationally accepted specifications for design and construction with bonded FRP reinforcement, the Missouri Department of Transportation has funded a research program aimed at validating the design and analysis procedure through strengthening and testing to failure of bridges under realistic highway loading and conditions. Two bridges, Bridge G270 and Bridge J857, were selected for this demonstration. Both bridges are solid reinforced-concrete (RC) slab bridges. Bridge G270 was strengthened to increase its load-carrying capacity by using externally bonded carbon FRP and is still in service. Two of the three deck slabs of Bridge J857 were strengthened with FRP composites. Elastic tests were conducted on Bridge G270 before and after strengthening. Laboratory and field tests were conducted to validate the analytical model and design capacity. The decks of Bridge J857 were tested to failure under static loads. Test results indicate that strengthening with FRP can increase the capacity of solid-slab bridge decks. Strength and failure modes can be predicted by using the classical approach for RC design and analysis, based on equilibrium and compatibility. The research program, strengthening techniques, test results, and modes of failure of the bridge decks tested are reported.