The crime of aggression will be included within the jurisdiction of the International Criminal Court once agreement is reached on its definition and the conditions for exercising jurisdiction. The author discusses the ultimately unsuccessful efforts of the now concluded Preparatory Commission for the Court to complete the drafting. He suggests how the mental and material elements of the offense might be structured consistently with other offenses in the Statute of the Court. Probably the biggest intellectual hurdle is that of “conditions.” A number of states, notably the Permanent Members of the Security Council, insist that there must be a predetermination of an act of aggression by a state made by the Security Council. Others believe that the predetermination can be made by the General Assembly or the International Court of Justice. Yet others claim that all decisions must be made by the International Criminal Court. The political choice between these positions has still to be made.