Students who perceive their instructors to endorse growth (vs. fixed) mindset beliefs report better classroom experiences (e.g., greater belonging, fewer evaluative concerns) and, in turn, engage in more behaviors that promote academic success (e.g., class attendance and engagement). Although many instructors personally endorse growth (vs. fixed) mindset beliefs, their students often perceive their beliefs quite differently. And, to date, little is known about how students come to perceive their instructors as growth-minded or as fixed-minded. To address this, the present research employs a social cognitive classification paradigm to identify teaching behaviors that students perceive as communicating instructors’ mindset beliefs. College students (NStudents = 186) categorized specific teaching behaviors (NBehaviors = 119) as signaling either fixed or growth mindset beliefs. Even after controlling for students’ personal mindset beliefs and the warmth of the teaching behavior, we found that when instructors suggest everyone can learn, offer opportunities for feedback, respond to struggling students with additional support and attention, and place value on learning it signals to students that their instructor endorses more growth mindset beliefs. Conversely, when instructors suggest that some students are incapable, fail to provide opportunities for feedback, respond to students’ struggle with frustration and/or resignation, and place value on performance and brilliance it signals to students that their instructor endorses fixed mindset beliefs.