The Ivory Coast's Taï Forest is home to a diverse primate fauna, including eight monkey species that interact daily with the environment, each other, and a web of predators. These interactions have led to an array of adaptations, some of which conform to theoretical expectations, and others are at odds with current behavioral ecology models. In this paper, we draw on fifteen years of observations to examine two central issues. First, how do broad trends in diet and resource distribution influence group size and levels of sociality? Second, what mechanisms are used to counter pressures exerted by the predator community? The general picture that emerges is that while the pressure exerted by predators at Taï has led to a host of behavioral and cognitive adaptations, it is food preferences and foraging habits, not predation pressure, that are the main determinants, not only of group size, but also its direct consequences - mating systems and sociality levels.