The extent to which university students read, write, speak, and listen in a range of registers is not completely understood, but such descriptions could lead to better designed curriculum for English learners. The purpose of this study is to estimate the proportions of time American university students spend reading, writing, speaking, and listening in various registers. The present study combines diary and survey techniques to describe the language use behavior for 53 university students. The results indicated that nearly half of university student language use time is spent listening (49.5 %), followed by reading (20.7 %), writing (18.2 %), and speaking (11.6 %). Students also engaged in 37 distinct registers, with face-to-face conversations (12.32 %), homework problems (10.70 %), and lyrical music listening (10.46 %) being the most frequent. This description of university student language use could be useful for ESL curriculum design and shows that proportional descriptions of language use are more feasible than previously asserted.