Building information modelling (BIM) promises to deliver one of the biggest advances in construction for the design team, including the cost planner. This chapter aims to introduce the concept and practice of BIM. It considers the definitions of BIM with its various facets. BIM is a relatively new tool in the construction industry and there is presently room for continuous improvement. Moderations to the project can be run through BIM to check for advantages or disadvantages, without any time or cost being wasted. There is a significant amount of research being undertaken into BIM, and with that research the modelling will be refined to reduce the negative aspects of its use. The chapter presents the benefits as well as the disadvantages of BIM to balance the review of BIM and its effect on design, construction and cost-planning practice. Finally, the art and practice of developing a BIM implementation plan in an organisation is presented.