1. This paper explores an approach based on simulation as an alternative to scripting the paths of each bird individually. 2. Flock animation is difficult to create. 2.1 It is made up of discrete birds yet overall motion seems fluid. 2.2 It is simple in concept yet is so visually complex. 2.3 It seems randomly arrayed and yet is magnificently synchronized. 2.4 The most puzzling is the strong impression of intentional, centralized control. Yet all evidence indicates that flock motion must be merely the aggregate result of the actions of individual animals, each acting solely on the basis of its own local perception of the world. 3. Key ideas: The simulated flock is an elaboration of a particle system, with the simulated birds being particles. The aggregate motion of the simulated flock is created by a distributed behavioral model much like that at work in a natural flock; the birds choose their own course. Each simulated bird is implemented as an independent actor that navigates according to its local perception of the dynamic environment, the laws of simulated physics that rule its motion, and a set of behaviors programmed into it by the ¡±animator¡±. The aggregate motion of the simulated flock is the result of the dense interaction of the relative simple behaviors of the individual simulated birds. 4. Limitations and future work 4.1 The internal animation of the geometrical model is ignored. Doing a believable job of melding these two aspects of the motion is more than a matter of concatenating the action of an internal animation cycle for the character with the motion defined by geometrical flight. There are important issues of synchronization between the current state of the flight dynamics model, and the amplitude and frequency of the wing motion cycle. Topics of current development include internal animation. synchronization, and interfaces between the simulation-based flock model and other more traditional. interactive animation scripting systems. 4.2 The behaviors that have been discussed in this paper are all simplistic, isolated behaviors of low complexity. The boids have a geometric and kinematic state. but they have no significant mental state.