This report looks back to the origin and history of the concept of the psychological contract and the increasing clarity gained from research into it in the last decade of the twentieth century. It also focuses on the intriguing findings of the research by Professor David Guest in 2000, which enabled us to look at the public sector in much greater detail for the first time. And lastly, it identifies the implications of this research for major change programmes in the public sector (particularly the civil service) and the possible areas of further research and investigation.