The current world trading system lacks a procedure to identify developing country Members, to whom "Special and Differential Treatment" (SDT) is granted. Based on the analysis of five methods of identifying developing country Members, which are GATT Article XVIII definition, listing, classification, self-designation by SDT grantees, and selection by SDT grantors, we argue that "self-designation," which is widely claimed as the basic method of identifying developing country Members, gives them little certainty and predictability in their rights and obligations in the world trading system. A procedure that can make precise identification of SDT beneficiaries is indispensable in order to fulfill the WTO's objective of development.