The decision on which language(s) of instruction to use and how to use them in education is a persistent challenge in the development of quality education in multilingual countries like Ghana. This qualitative study of four public basic schools in the Ashanti region of Ghana explores teachers' and pupils' experience of the early-exit transitional education policy in Ghana to understand how it is implemented in the classroom and what its outcomes are for learning. It was discovered that linguistic heterogeneity within classrooms remains a challenge to effective communication despite bilingual instruction. This is exacerbated by the inadequate supply of teaching and learning resources and cognitive underdevelopment of the mother-tongue. The interaction of these factors makes only three years of bilingual instruction insufficient for children to develop adequate bilingual ability to advance intellectually after primary three with English-only instruction. This is more so the case for children at the primary level whose L1 is a marginal/non-dominant language linguistically different from the L1 of their classroom.