ISD projects are characterised by complexity because they are situated in an unstructured environment where requirements are dynamic and the technical solution is potentially unknown. In this context existing tools, routines and methodologies may not be sufficient to resolve the complexity that emerges during the project life span. The resolution of complex issues requires access to a broad range of experience and knowledge and the ability to apply that knowledge to the specific requirements of the project. Knowledge processes, such as experimentation, sense making and learning, amongst others, represent an innovative and flexible means to address the intrinsic complexity of ISD projects. In this chapter we argue that knowledge processes must be explicitly incorporated into project management in order to resolve emergent issues and integrate knowledge created by those practices into project management tools, techniques and methodologies. The chapter presents a study of the rollout of an enterprise project management software project in an Australian government department to illustrate the role of knowledge processes to resolve complex issues and how these processes became incorporated into the emergent methodology used to manage the project.