A method and system for interfacing an application program with a compound document storage system. The present invention provides an interface which an application program uses to manipulate compound documents. In a preferred embodiment, this interface is implemented in a multilayered architecture. The first layer provides methods which an application program uses to access a compound document using the functions of the second layer. The second layer maps requests to store data in the compound document to a storage format using the functions of the third layer. The third layer maps requests to write to a file to an arbitrary storage medium.