The Extradosed Prestressed Bridge represents a relatively new bridge type. The first of this type bridge was constructed in Japan in 1994, and Japan has since built at least 29 examples of this bridge type. Throughout the rest of the world, another 34 of this bridge type have been built, with most countries having only one, or at most a few, examples. A broader application of this bridge type has been hampered by lack of design information and in particular lack design criteria for the stay cables. The purpose of this dissertation is to progress the understanding and application of this bridge type by providing (1) a summary and discussion of extradosed bridges constructed worldwide, (2) an assessment and recommendations on proportioning parameters, characteristics and features of extradosed prestressed bridges, and (3) a contribution of a new design approach for the stay-cable design for extradosed prestressed bridges. Also presented is an application of the above to a real-world prototype design to assess and comment on the application of the recommended proportioning parameters, characteristics, features and the new approach to stay cable design criteria.