his diploma thesis is about the design of generic architecture used to integrate document-centric content stored in IBM Lotus Notes into a Java based and process driven enterprise portal. Starting with an introduction of the main concepts and technologies, an integration strategy is identified. This strategy is based on an evaluation of integration technologies and levels from both the technical and business perspective. Then requirements of a cross-system application architecture are presented and according to them a tiered architecture is designed. The applicability of this architecture is tested by a sample application developed to prove the concept. This application was realized with IBM Lotus Notes 6.5, IBM WebSphere Portal 5.1 and the open source application framework Spring 2.0. This paper gives hints on how to integrate existing Notes applications into a portal and how to design new applications to be integrated.