This study investigates mathematics learning deficits among Xhosa-speaking learners in Langa township, Cape Town. It explores how language barriers, socio-economic factors, and instructional practices contribute to underperformance in mathematics. With a focus on the transition from mother-tongue (isiXhosa) to English instruction, the research examines the challenges learners face in understanding mathematical concepts. Using a qualitative case study approach, data will be collected through interviews, focus groups, classroom observations, and document analysis. The study aims to provide insights that can inform more effective, inclusive teaching strategies and contribute to improving mathematics outcomes in under-resourced, multilingual learning environments.