This research study aims to evaluate how the trilingual policy (Kinyarwanda, French and English) is implemented in Kigali City’s nursery and primary schools in terms of facilitating learners’ cognitive academic language proficiency (CALP) development, in both the pre-2008 and post-2008 language policies. It is an exploratory-qualitative-interpretative research study, which analyses the language preference, the age of change-over and the multilingual models adopted and how they contribute to learners’ CALP development. It also analyses the implications of the post-2008 policy. The findings indicated that initial bilingualism, initial trilingualism, early total immersion and gradual transfer models were implemented in the pre-2008 policy; while the post-2008 policy implements early total immersion. The learners’ CALP in both the MT and the AL could be more developed in public schools under the pre-2008 policy due to exposure to Kinyarwanda instruction from the start but it may not be developed fully under the post-2008 policy, because English is used as MOI from the onset of education. / Linguistics and Modern Languages / M.A. (Applied Linguistics)