Selection of power and propulsion system architecture is one of the most far-reaching and irreversible decisions made by the designer of a modern ship. However, most texts and design handbooks pay little attention to the implications of this design decision nor is sufficient attention paid to the attributes of the various alternatives available to the ship designer/owner. Integrated power systems, made possible over the past three decades by the advances in modern high-power power electronics, provide many benefits to the ship owner, including reduced operating costs, arrangement flexibility, superior reliability and survivability, and support for advanced weapons on sensors warships. This paper will outline the architecture options available to today's ship designer and will discuss the design implications and pitfalls inherent in the power system architecture selection, paying particular attention to the unique aspects of integrated power systems.