Shareholders’ Agreements are contractual devices to manage tensions among shareholders of a corporation. These agreements have a wide scope related to shareholders’ interest. Nevertheless, before subscribing a shareholder agreement is important to determine the requirements to make it enforceable. This issue has been addressed in the last twenty years by state corporate statutes following the Model Business Corporation Act and the Delaware General Corporation Law and in different court decisions. Today, shareholders’ agreements will be enforced according to the terms defined by the parties unless the agreement injures non-participating shareholders, third parties or is against public policy.