In 2001, the Bridge Office of the Ministry of Transportation of Ontario, Canada, initiated a research project to investigate the use of pre fabricated bridge technology as an innovative approach to bridge construction and ehabilitation. Two potential prefabricated systems were investigated: prefabricated composite slab-on-girder beam elements connected with cast-in-place concrete closure strips and full-depth prefabricated concrete deck-slab panels laid across new or existing girders and connected with cast-in- place concrete closure segments. The proposed systems are applicable to bridges that use steel or concrete girders and trusses as longitudinal load- carrying members. This paper presents the findings of a series of laboratory tests that were performed on scale models to study the overall structural behavior of the bridge systems under service loads, the long-term load effect on the longitudinal cold joints, and the ultimate punching-load capacity of the concrete deck slab. The test specimens were subjected to a minimum of 7 million load cycles, after which ultimate-strength tests were conducted on the deck slabs. Overall, the test results demonstrated the excellent performance and integrity of the prefabricated bridge systems under the applied test loads.