Graduate teaching assistants (TAs) play an important role in undergraduate programs in our Earth Science Department. A course on teaching and learning was developed to train graduate students in student-centered pedagogy, in a discipline-specific context. The training course has been running for a decade and has been taken by over 100 graduate students. This article describes the development of the course and investigates the impact on graduate students' beliefs about science teaching and learning. Responses to the Beliefs About Reformed Science Teaching and Learning survey indicate that students who have taken the course hold beliefs that are more consistent with research-based principles of how people learn about science than students who have not taken the course. Data from course evaluations and pre- and postcourse surveys demonstrate that taking the course also improves confidence in teaching ability and impacts graduate students' approaches to teaching and their own learning. This course offers effective pedagogical training that gives graduate students the tools to develop and improve their teaching both as TAs and as future faculty members.