In this qualitative case study, we investigated the role of an advanced math curriculum with language scaffolding on the development of geometric and visual-spatial reasoning skills in young mathematically promising English learners (MPELs). Specifically, we examined the effects of providing MPELs with challenging and supportive math curriculum to facilitate the development of mathematical potential through a geometry unit. Twenty-one MPELs were randomly assigned to either an intervention or a comparison class. The data sources included audio recordings of class sessions, documents of math tasks, field notes, and test scores. Findings revealed that in the intervention class, tasks required more cognitive demands, and students were encouraged to contribute to classroom discourse more than in the comparison class. MPELs in the intervention class demonstrated greater gains in geometric reasoning compared to their peers in the comparison class. These findings underscore the point that challenging and supportive curricula can effectively nurture the mathematical potential of underrepresented gifted students.