Now entering its 16th year, the International Geobiology Course is an intense, multidisciplinary summer course exploring the coevolution of the Earth and it’s biosphere, with an emphasis on how microbial processes affect the environment and leave imprints on the rock record. Participants get hands-on experience in cutting-edge geobiological techniques, learn from a broad team of eminent scientists in the field, and work in research groups to solve relevant questions. Geobiology 2019 begins with a 10-day field trip to the Mammoth Springs area of the Eastern Sierra, to study hot springs, ancient sedimentary rocks and fossils, and the modern biogeochemistry of Mono Lake, as well as the coast near Ventura, CA to see sulfur springs and a world-famous exposure of the Monterey Formation. The course then returns to Caltech in Pasadena for ~2 weeks of laboratory instruction and hands-on experience with many of Caltech’s cutting edge facilities and instrumentation. We finish with 11 days at the Wrigley Marine Center on beautiful Catalina Island, learning from a rotating cast of geobiology instructors and working on project data. Geobiology 2019 is open to all graduate students and postdocs interested in pursuing geobiologic research as a career. We expect to admit 16 participants this year via competitive admissions. Preference is generally given to those in the midst of their program, rather than at the very beginning or end. Postdocs with training in other fields who want to work in geobiology are encouraged to apply. Applicants from around the world, including developing nations, are encouraged to apply. Financial aid is available for those with demonstrated need. Applications are due by February 8, 2019.