The psychological contract has captured the attention of researchers as a framework for understanding the employment relationship. In terms of research, there has been an exponential growth in publications on the topic in the last 15 years (following the publication of Rousseau's 1989 article) giving the impression of a relatively new concept. Its introduction can however be traced to the 1960s. The concept developed in two main phases: its origins and early development covering the period 1958 to 1988, and from 1989 onwards. This chapter begins with a review of the initial phase in the development of the psychological contract highlighting the commonalities and differences amongst the early contributors. We then review Rousseau's (1989) reconceptualization of the psychological contract, as this has been very influential in guiding contemporary research. The two distinct phases in the development of the psychological contract have given rise to a number of key debates, which we discuss prior to outlining an agenda for future research