Abstract: In this chapter, prepared for The Oxford Handbook of New Private Law, we identify the principal ways in which the common law trust has been used as an instrument of private ordering in American practice. We argue that in both law and function, contemporary American trust law has divided into distinct branches. In our taxonomy, one branch involves donative trusts and the other commercial trusts. The donative branch divides further to include separate sub-branches for revocable and irrevocable donative trusts. We explain the logic of this branching in both practical function and doctrinal form.