In this paper, the authors propose and validate a methodology for the development of integrated Information Technology (IT) infrastructures. The motivation for putting forward a new methodology is grounded on the limitations of the various software engineering methodologies (traditional) that exist today. Despite that the traditional methodologies result in the development of Information Systems (IS) from scratch, Enterprise Application Integration (EAI) builds integrated IT infrastructures using existing applications. This significant difference is associated with many issues needed to be realised and addressed like: (a) the changes that such an infrastructure brings to organisations, (b) the resistance to change and (c) the extension of IS lifecycle’s. The proposed methodology consist of eight stages and aims at supporting software engineers, organisations and researchers to build integrated IT infrastructures. As a result the methodology seeks to contribute to the body of knowled...