Abstract: In this paper, we present a novel method for controlling massive crowds by using control particles. Our method differs from previous ones that generate attraction (or repelling) forces around the control particles. Instead of doing this, we create a steady-state, flow-like control field that guides the crowd to move along with the control particles. Our control field can be naturally incorporated into the original simulation by using density-based weighted blending. Although we focus on simulation methods that use dynamic potential functions, our method can also be used to improve the controllability of agent-based simulation methods. Since the control particles can be easily manipulated by traditional key-framing, our method provides animators with an intuitive interface for manipulating the position of crowd over time. We illustrate the effectiveness of our method on several examples.