The national mandate to develop a National Health Information Network (NHIN) requires the design and implementation of interoperable electronic health record (EHR) systems in hospitals, insurance carriers, urgent care, hospices, and private practices. First movers provide reference implementations and help guide the discussion of further NHIN building blocks. This paper discusses interface considerations in a Web-based pediatric EHR system, PedOne that provides scheduling, billing, and doctor and nurse interview capabilities. The interface is based on a user-centric model and seeks to capture practice workflow in an intuitive manner. PedOne uses open standards to ensure interoperability and conform to stated NHIN design goals. The paper concludes with a discussion of how the current implementation might evolve as more pieces of the NHIN fall into place.