Considerable progress has been made in understanding the sensory and motor functions of the superior colliculus and how these interact to produce behavioral responses. The organization of the sensory and motor maps, and the close relationship between them, has rendered this midbrain structure the region of choice for addressing a number of fundamental questions in neuroscience. Indeed, the superior colliculus has even been referred to as a microcosm of the brain as a whole.Firstly, the superior colliculus has become a model system for multisensory neurons located elsewhere in the brain as well as for other aspects of perception and behavior that depend on interactions between different sensory inputs. Secondly, developmental studies of the superior colliculus in a range of species have provided valuable insight into mechanisms underlying the formation of sensory maps. Thirdly, the superior colliculus has been used to investigate the coordinate transformations needed to translate diverse sensory inputs into motor commands and the approaches used to do this have now been successfully applied to other brain regions involved in sensorimotor integration.Finally, in terms of its motor output, the superior colliculus is the most thoroughly understood component of the network of cortical and subcortical structures that act together to select and generate orienting movements, and many models of oculomotor control are based on the physiological properties and anatomical connections of its neurons. Indeed, future investigations of the superior colliculus – perhaps more than any other brain region – are likely to reveal how the sensory cues associated with objects and events in the world give rise to appropriate motor responses.