This paper describes the motivation, requirements, and challenges of integrating a geospatial infrastructure, based on standardized web services, into an earth observation (EO) data library. The design of harmonized data and information models of the EO and geospatial community is a precondition for interoperability at metadata, data and semantic levels. A major challenge arises from raising the awareness that interoperability is essential for an interdisciplinary use of EO data in Geographic Information System (GIS) and value-adding services.