This article analyses the dynamic character of relationships between superiors and employees in the context of a psychological contract. One of the assumptions is that superiors and employees’ shared understanding of their mutual obligations and expectations underpins the performance of the psychological contract. The article explains the concept of a psychological contract and addresses possible breaches thereto as well as their impact on the shape of relationships between superiors and employees. Information necessary to carry out the analysis was obtained from surveys conducted with 178 representatives of large and medium-sized firms based in Poland and with 800 of their employees. In addition to determining the state and contents of a psychological contract as felt by superiors and employees, the article provides also a description and the rankings of their mutual expectations and obligations related to a psychological contract. The degree of similarity between the opinions of the surveyed superiors and employees on each other’s obligations and expectations was assessed with a specially constructed index (an opinion coincidence index, OCI). The results of the surveys and the direction and amount of OCI’s deviation from show that while employees and superiors frequently differ in the perceptions of their expectations and obligations, there are also areas where their opinions are identical. It has also been found that employees’ perception of the contents of a psychological contract depends on their age and the number of years they have worked in the organisation. This fact points to the dynamic character of a psychological contract.