Once considered the province of philosophy and the behavioral sciences, the process of making decisions has received increasing scrutiny from neurobiologists. Recent research suggests that sensory judgements unfold through the gradual accumulation of neuronal signals in sensory-motor pathways, favoring one alternative over others. Stored representations of the outcome of prior actions activate neurons in many of these same areas during decision-making. The challenge for neurobiologists lies in deciphering how signals from these disparate areas are integrated to form a single behavioral choice and the mechanisms responsible for selecting the appropriate information upon which decisions should be informed in particular contexts.