The U.S. Supreme Court has insisted that standing doctrine is a “bedrock” requirement only of Article III. Accordingly, both jurists and scholars have assumed that the standing of the executive branch and the legislature, like that of other parties, depends solely on Article III. But I argue that these commentators have overlooked a basic constitutional principle: federal institutions must have affirmative authority for their actions, including the power to bring suit or appeal in federal court. Article III defines the federal “judicial Power” and does not purport to confer any authority on the executive branch or the legislature. Executive and legislative standing instead depend in large part on the provisions conferring power on those institutions—principally, Article II and Article I. This basic insight has important implications. I argue that the Take Care Clause of Article II helps both to explain the breadth and to define the limits of executive standing. The executive branch has standing only insofar as it has an Article II power and duty to enforce and defend federal law on behalf of the federal government. The Take Care Clause does not, however, confer standing when the executive no longer asserts that law-enforcement interest—when it declines to defend a federal law. Article I, for its part, does not confer any power on Congress to enforce or defend federal laws in court. Accordingly, contrary to the assumption of many scholars, Congress lacks standing to represent the United States in place of the executive. The Supreme Court has entirely overlooked these questions of institutional power in considering issues of executive or legislative standing, including, most recently, in the litigation over the Defense of Marriage Act. Article III cannot confer power on the executive or the legislature that Article II or Article I denies.