Organisations face ever growing complexity in the business environment and use processes to deliver value in a stable, sustainable and controllable way. However complexity in the business environment is threatening the stability of processes and forcing their continuing evolution in ever shorter time cycles, which then creates significant management challenges. Addressing complexity requires a change in management thinking about processes. The research explores the nature of complexity, how businesses respond to it, and the consequent impact on process complexity. The research reviews the notion of complexity and its relevance to organisations, business processes and knowledge contexts. The research focuses on knowledge intensive firms, as these exhibit several of the features and allow early application of the approach suggested by this thesis. The research draws upon concepts from several fields including complexity and complex systems, business process management, and knowledge management. This thesis addresses the question: “How can organisations address the complexity of knowledge intensive business processes?” In answering the question the thesis argues the need to integrate multiple perspectives involved in managing such processes, proposes an approach to complex knowledge intensive business processes that reduces the management challenge, and argues the need to develop an agile shared knowledge context in support of the approach. This thesis develops a theoretical framework consisting of a set of hypotheses rooted in the literature, and then proposes an approach to addressing complex knowledge intensive business processes based upon these hypotheses. Then,through a series of QDS investigations and action research cycles, this thesis tests the hypotheses, further develops the approach and examines its application in different problem domains in multiple organisations. This thesis then discusses the process and the outcomes of applying the approach, identifies its limitations, assesses its contribution to knowledge and suggests directions for further research.