The article explores the extent to which the Security Council has the legal authority to authorize regional (defence) organizations to enforce military measures on its behalf. In the process it identifies Article 53(1) of the Charter, as well as Articles 42 and 48(2) as the clauses that could facilitate such action. Whereas the first enables enforcement action between the regional organization and its members, the latter two allow for the military utilization of regional organizations outside of their territory and/or against non-members, as well as the military utilization of other organizations such as regional defence organizations. Thereafter, it explains how the centralization of the use of force within the Charter structure requires the Security Council to remain in overall control of the authorization. This factor, in combination with the `opt-in' character of Chapter VII decisions, necessitates the explicit and prior nature of the authorization. In addition, it implies that authorizations that are not subjected to an explicit time limit and from which no functional limitation can be derived, will only remain legal as long as they are supported by all five permanent members of the Security Council. The potential implications of these principles are illustrated with reference to the practise of Security Council with respect to ECOWAS in Liberia and Sierra Leone, as well as NATO in former Yugoslavia.