This article advances the prerequisite network as a means to visualize the hidden structure in an academic curriculum. Networks have been used to represent a variety of complex systems ranging from social systems to biochemical pathways and protein interactions. Here, I treat the academic curriculum as a complex system with nodes representing courses and links between nodes the course prerequisites as readily obtained from a course catalogue. I show that the catalogue data can be rendered as a directed acyclic graph, which has certain desirable analytical features. Using metrics developed in mathematical graph theory, I characterize the overall structure of the undergraduate curriculum of Benedictine University along with that of its Biochemistry and Molecular Biology program. The latter program is shown to contain hidden community structure that crosses disciplinary boundaries. The overall curriculum is seen as partitioned into numerous isolated course groupings, the size of the groups varying considerably. Individual courses serve different roles in the organization, such as information sources, hubs, and bridges. The curriculum prerequisite network represents the intrinsic, hard-wired constraints on the flow of information in a curriculum, and is the organizational context within which learning occurs. I explore some applications for advising and curriculum reform.