Abstract: Accounts of private law in general and property in particular have downplayed traditional notions of system in favor of a sum-of-the-parts reductionism. Recent developments in complex systems theory allows a reassessment of this picture. A system is a collection of elements and the connections between and among them; complex systems are ones in which the properties of the system as a whole are difficult to infer from the properties of the parts. Private law is a complex system. Taking the bundle of rights in property law as a starting point, the chapter shows that conventional analysis is overly reductive in that it assumes that the attributes of the whole bundle are the additive sum of the attributes of the “sticks” in the bundle taken individually. Theoretically and empirically, this aggregative approach is not as accurate as one based on “organized complexity,” points in the direction of the New Private Law: systems theory leads to a better and more unified account of the bundle of rights, standardization in property, possession, title, and equity. Systems theory also promises to mitigate some of the dichotomies in private law, such as holism versus reductionism, homogeneity versus specialization, formalism versus contextualism, and public versus private law.