The objective of this ethnographic case study is to describe in detail one professor's translanguaging practices in an undergraduate science course at an officially bilingual university. The data-set is comprised of ethnographic field notes of 11 observed classes, audio recordings of those classes, an interview with the professor, and artifacts including the professor's presentations, academic readings assigned, quizzes, and exams. Translanguaging practices--moments when both Spanish and English were used in presentation of academic content--are identified, analyzed, and presented in detail. Results show that translanguaging was strategic, dynamic, and woven through the presentation of academic content. In addition, translanguaging served to apprentice the Spanish-dominant students into English for scientific purposes. The translanguaging practices documented here illustrate the possibilities for other multilingual university classrooms around the world.