Previous research supporting differentiated instruction (DI) has led to its adoption in different countries as a promising pedagogical framework for addressing diverse learners' needs. To date, there exists little information on DI from Tanzania especially when competence-based education and inclusion are being embraced. To address this gap, this study explored how Tanzanian teachers perceived DI in their working with academically high-achieving secondary school students. The study was strongly informed by a constructivist research tradition, adopting a multiple case study design. Focus group discussions and interviews were used as data sources and thematically analyzed. The analysis revealed teachers' limited perceptions of DI, although consonance with the existing literature on DI practices for high-ability learners. After discussing the findings, as conclusion, the article stresses the importance of training teachers on DI to enhance their instructional practices for high-ability learners in Tanzania, along with setting the grounds for future research.