Educational policies seek to integrate engineering instruction within elementary school settings. This becomes challenging for elementary school leaders and teachers, as few have previous teacher preparation or professional development experience with engineering content or processes. Although studies have considered teacher identity in relation to new teachers' experiences teaching unfamiliar STEM (science, technology, engineering, and math) content, few consider the experiences of veteran teachers, especially regarding teaching of engineering. Utilizing the lenses of brokering and boundary crossing, this 2-year interpretive case study explores the ways in which 3 veteran teachers reflected on teaching engineering and the engineering design process in a newly formed after-school elementary engineering club. Teachers' reflections elucidate how they mediated their experiences in becoming familiar with new engineering content by navigating boundary crossing and drawing from and expanding on their teacher identities while enacting real-world practices of teaching and working with children.