Postdoc grant: The beliefs that children hold regarding the malleability of their own intelligence and academic ability are highly predictive of their motivation, engagement, and achievement in school. The origin of these self-theories, however, is unknown. What leads children to believe that they can improve their ability by investment and hard work or, conversely, to believe that their ability is fixed and there is nothing they can do to change it? The proposed research aims to study how the feedback received from teachers during children’s success and failure experiences in mathematics class gives rise to children’s self-theories of intelligence. While it is theorized that this is the mechanism behind self-theory development, the current project aims to empirically elucidate this mechanism. This will be done by zooming in on teacher-child interactions that occur within one class, and how they develop across the year during primary education, focusing specifically on teacher feedback and children’s engagement, persistence, and achievement during the task. Moreover, I will examine how different developmental trajectories predict the emergence of children’s self-theories of intelligence. This research promises to provide insight regarding the origin of self-theories of intelligence that is needed in order to encourage development of adaptive self-theories within classrooms.