As the Internet evolves into a global communication infrastructure, there is a growing need to support powerful and flexible services such as traffic management and quality of service. Over the past decade, two classes of solutions have emerged: those maintaining the stateless property of the original IP architecture (e.g., Differentiated Services), and those requiring a new stateful architecture in which routers have to maintain and manage per-flow or per-connection state (e.g., Integrated Services). While stateless solutions are more scalable and robust, stateful solutions can provide services with higher flexibility, utilization, and assurance levels. In this talk, I will present a novel technique and network architecture that bridge this long-standing gap between stateless and stateful solutions. The key idea behind this technique, called Dynamic Packet State (DPS), is that, instead of having routers maintain per-flow state, packets carry this state. Based on DPS, we have developed a network architecture called Stateless Core (SCORE) in which core routers do not maintain any per-flow state. Yet, by using DPS, a SCORE network can provide services which are as powerful and flexible as the services provided by a stateful network.