A Practice Note addressing the standing requirements for a derivative action brought by a shareholder of a corporation or a member of an alternative entity, such as a limited liability company or a partnership. This Note defines the elements that a plaintiff must allege and prove to show standing, including the contemporaneous and continuous ownership requirements under Delaware and federal rules and common law, and discusses exceptions to these share ownership requirements for double and multiple derivative actions, shares that devolve on the plaintiff by operation of law, and cases involving the continuing wrong doctrine, the merger-fraud exception, and the mere reorganization exception. It also provides guidance for counsel challenging a plaintiff's standing at critical stages in the litigation.