An application program interface (API) is provided for requesting, storing, and otherwise accessing data within a health integration network. The API facilitates secure and seamless access to the centrally-stored data by offering authentication/authorization, as well as the ability to receive requests in an extensible language format, such as XML, and returns resulting data in XML format. The data can also have transformation, style and/or schema information associated with it which can be returned in the resulting XML and/or applied to the data beforehand by the API. The API can be utilized in many environment architectures including XML over HTTP and a software development kit (SDK).