In recent years, the U.N. Security Council has repeatedly come under criticism for its inaction in the face of serious violations of international law. As a means to prevent further deadlocks, this article advocates the introduction of a duty to explain votes cast in the Council. In certain situations, such a duty to give reasons already exists today, although it is not implemented. We propose to extend this duty to all votes in the Security Council and to codify it in its Provisional Rules of Procedure. A comprehensive duty to give reasons has three major virtues: it increases the quality of Council decisions, it enhances legal certainty, and it improves the accountability of the Council and of its members. As opposed to structural reforms, our proposal does not necessitate amending the U.N. Charter and thus does not depend on the consent of the Council’s permanent members.