The relationship between employees and companies can be understood purely economically as an exchange of labor for money. This exchange relationship is legally secured by an employment contract, which also defines other characteristics of the relationship, such as working hours and conditions for terminating the contractual relationship. However, in addition to the economically and legally defined relationship between employee and employer, there is always also a psychological relationship based on social exchange. This book focuses on the design of this relationship. The concept of the psychological contract includes obligations, promises, expectations, contributions from the company, or inputs from employees that are exchanged in an employment relationship beyond the legal employment contract. Central questions of the psychological contract are addressed.