This article advances the prerequisite network as a means to visualize the hidden structure in an academic curriculum. Network technologies have been used for some time now in social analyses and more recently in biology in the areas of genomics and systems biology. Here I treat the curriculum as a complex system with nodes representing courses and links between nodes the course prerequisites as readily obtained from a course catalogue. The resulting curriculum prerequisite network can be rendered as a directed acyclic graph, which has certain desirable analytical features. The curriculum is seen as partitioned into numerous isolated course groupings, the size of the groups varying considerably. Individual courses are seen serving very different roles in the overall organization, such as information sources, hubs, and bridges. This network represents the intrinsic, hard-wired constraints on the flow of information in a curriculum, and is the organizational context within which learning occurs.