There has been little attention given to teaching beliefs of graduate teaching assistants (GTAs), even though they represent the primary teaching workforce for undergraduate students in discussion and laboratory sections at many research universities. Secondary school education studies have shown that teaching beliefs are malleable and can be shaped by professional development, particularly for inexperienced teachers. This study characterized inexperienced GTAs' teaching beliefs about student learning and how they change with a science-specific pedagogy course that emphasized student learning. GTA teaching beliefs were characterized as traditional (providing information to students), instructive (providing activities for students), and transitional (focusing on student-teacher relationships). At the start of the course, traditional, instructive, and transitional beliefs were emphasized comparably in the concept maps and presentations of inexperienced GTAs. At the end of the course, although GTAs' beliefs remained mostly teacher focused, they were more instructive than traditional or transitional. GTAs included teaching strategies and jargon from the course in their concept maps but provided minimal explanations about how opportunities for active student engagement would impact student learning. These results suggest there is a need to provide ongoing discipline-specific professional development to inexperienced GTAs as they develop and strengthen their teaching beliefs about student learning.