Article 12(3) of the Rome Statute provides a mechanism for a non-State Party to accept the jurisdiction of the International Criminal Court by lodging a declaration with the Registrar. In doing so, that State agrees to take on obligations of cooperation with the Court that it would otherwise not be under. There have already been declarations lodged by two States and the possibility exists that this mechanism may be utilized more frequently than had been originally envisaged. Yet, the procedures that have followed these two declarations have taken different paths, with one situation being the subject of judicial scrutiny at an early juncture while the other remains at the preliminary evaluation stage without any judicial involvement. These differences are not wholly explained by the different factual circumstances, but are also due to the uncertain language in the legal texts. This article discusses the ambiguities that surround the declaration mechanism under the terms of the Statute and the other legal texts, focusing in particular on the procedural questions that arise from the lodging of a declaration as well as the scope to which the non-State Party can restrict the terms of a declaration. Although it would be preferable to address these ambiguities by way of amendment to the texts, this might not be a politically acceptable approach at this early stage in the Court's activities. This article therefore offers some suggestions as to how to deal with the uncertainties within the Statute as they relate to the declaration mechanism on the basis of the existing provisions.