The aim of EFIS 2001, the fourth workshop in the sequence of the international workshops on engineering federated information systems is to intensify the exchange of ideas and experiences between academia and industrial practice. EFIS 2001 was embedded as one part into the major event, Information Federation Week Berlin 2001, including scientific and industrial workshops, demos and discussions for the academic audience as well as for a broader of young and senior practitioners in industry and public services. This volume includes eight research papers covering different aspects from the following topics of the IFW 2001: modelling in analysis and design of FIS; software architectures for FIS; component-based engineering of FIS; metadata for FIS; managing heterogeneous information sources; middleware platforms for the construction and operation of FIS; web technologies in FIS solutions, including XML approaches; technological support for the integration of legacy systems; CASE tool support for the development of FIS; evolution of FIS as long-lived information infrastructures; domain-specific solutions in the design of FIS; and evaluation of FIS approaches.