The dozens of studies on academic discourse carried out over the past 20 years have mostly focused on written academic prose (usually the technical research article in science or medicine) or on academic lectures. Other registers that may be more important for students adjusting to university life, such as textbooks, have received surprisingly little attention, and spoken registers such as study groups or on-campus service encounters have been virtually ignored. To explain more fully the nature of the tasks that incoming international students encounter, this article undertakes a comprehensive linguistic description of the range of spoken and written registers at U.S. universities. Specifically, the article describes a multidimensional analysis of register variation in the TOEFL 2000 Spoken and Written Academic Language Corpus. The analysis shows that spoken registers are fundamentally different from written ones in university contexts, regardless of purpose. Some of the register characterizations are particularly surprising. For example, classroom teaching was similar to the conversational registers in many respects, and departmental brochures and Web pages were as informationally dense as textbooks. The article discusses the implications of these findings for pedagogy and future research.