This monograph offers an in-depth analysis of the crime of aggression as covered by the Rome Statute of the International Criminal Court. Starting from the legal history of its inclusion in 2010, it analyses the relevant articles 8bis, 15bis and 15ter of the Rome Statute – covering the definition of the crime of aggression, the exercise of jurisdiction over the crime of aggression through State referrals and the proprio motu powers of the ICC Prosecutor, and the exercise of jurisdiction over the crime of aggression through UN Security Council referrals. Likewise, the book covers upcoming developments on the crime of aggression and the ICC post-2017 (the year when a decision about the activation of the Court’s jurisdiction on the crime will probably be made). It addresses the various challenges towards activating the Court’s jurisdiction, in particular, the necessary vote required for activation, as well as the significant challenges faced by the three ways in which the Court may exercise such jurisdiction.