This note describes the Service Allocation Profile scheme for differential service allocation within the Internet. The scheme is based on a simple packet drop preference mechanism at interior nodes, and highly flexible service profiles at edges and inter- provider boundary points within the net. The service profiles capture a wide variety of user requirements and expectations, and allow different users to receive different levels of service from the network in a scalable and efficient manner. The note describes the basic form of the mechanism, discusses the range of services that users and providers can obtain by employing it, and gives a more detailed presentation of particular technical, deployment, standardization, and economic issues related to its use.