Are teachers' growth mindsets associated with the development of their students? We know that teacher growth mindset (TGM) shapes the attributions teachers make about their students' abilities and can lead to assumptions about the role that perceived stable traits play in students' performance; however, to date, research has not focused on the relationship between TGM and the development of student growth mindset. This study fills a gap in our knowledge by testing this association over time. Findings from an analytic sample of 57 teachers and 1957 intervention students reveal that teachers with growth mindsets have a mild positive and statistically significant association with the development of their students' growth mindsets, particularly for boys. Implications for teacher education, practice, and future research are discussed.