Collective behavior is embodied in swarms of insects, flocks of birds, herds of antelope, and schools of fish. In each of these cases, individuals move through their environment and respond to threats and opportunities almost simultaneously, forming an undulating enclave that seems to operate as a single entity. Such coordinated movement requires the rapid and efficient transfer of information among individuals, but understanding exactly how this information spreads through the group has long eluded scientists. Studying this behavior in schools of fish has been incredibly challenging, because the cues that drive it occur at lightning speed, come from multiple directions and sources, and of course because all of it takes place underwater. Now, Iain Couzin and his colleagues at the Max Planck Institute for Ornithology at the University of Konstanz, Germany are using new observation techniques and technologies—including high-speed video, motion-tracking software, and advanced statistical modeling—to reveal the mysterious mechanics of schooling fish. Their findings may shed light on the evolution and benefits of collective behavior across the animal kingdom.