It is widely accepted that design changes, occurring during construction projects, can account for a significant proportion of the engineering design consultant's total cost. Projects with multidisciplinary, distributed and virtual project teams, working on technically challenging problems, make the impact of design changes increasingly difficult to predict. Existing guidance suggests 'best practice' protocols for recording, reporting and communicating design changes. However, best practice protocols do not provide guidance for predicting the impact in terms of project cost and duration. Impact assessments are essential in the decision to implement changes and subsequently being in a position to justify fee claims to clients. Decisions in the construction process are normally based on experience and professional knowledge of practitioners, such as architects, engineers, project managers and contractors. There is evidence, however, that, in design management, sharing of professional knowledge tends to be tacit and socially constructed (where team members draw on their own experience and the experience of those around them). Although practitioner experience and intuition is invaluable in determining the impact of a design change, this research is based on the position that a more structured process is required. It is argued that a software based approach, to better inform practitioners' existing knowledge, is required to improve the quality and accuracy of impact assessments. The current practice for managing and assessing change was examined through studying the operations of the case study organisation, undertaking a literature review and conducting interviews with representatives from organisations in other industries.A new project management tool was then developed which provides support for practitioners to make better-informed impact assessments. This is achieved through providing: (a) a process map to visualise rework, (b) instant access to previous similar impact assessments and (c) an embedded, standardised method for knowledge sharing. The concept for this tool was developed by combining appropriate techniques and tools found in the design management and knowledge management literature. Users are further encouraged to use the software tool through a system to automate the updating of Microsoft Project schedules, thus eliminating time currently spent scheduling rework. The validation and verification stages consisted of formal interviews with potential users and preliminary user testing. Regular feedback on the support tool was obtained from a wide range of peers and potential users and this was then used to develop its functionality. Positive feedback has included comments about the concept of the tool, user-friendliness and need for implementation.