The concept of contract is a key concept in organization science. It is variously defined as the term labels many forms of obligations and exchanges. Some are voluntary, some are not, some are market-based, some relational. It opens the notion of a broad conceptualization like a word with many definitions that all same to have some form of governance. In this e-book these various forms will first be tackled prior to comparing the notion of social contract with psychological contract based on two criteria: an anthropology of the individual and an anthropology (a set of values) of the contract.