Language Discordance and its Moderating Effects on Early-Grade Bilingual Reading Intervention Outcomes in Ghana

Improving early-grade reading in linguistically diverse, resource-constrained settings remains challenging. This study evaluated a nationwide bilingual reading intervention in Ghana that provided reading materials, teacher guides, sequenced training, and ongoing coaching. Using a randomized trial with 3,559 second- and third-grade students in 198 schools, we examined program impacts and how student, teacher, and school languages moderate these effects. The intervention improved reading outcomes across letter-sound knowledge, decoding, fluency, and comprehension, yielding main effect sizes of 0.09 to 0.43 standard deviations for Ghanaian languages and 0.12 to 0.37 standard deviations for English. These gains were amplified when students and teachers shared the same first language for classroom oral exchanges. Effect sizes for students in concordant student-teacher pairs were 0.17 to 0.42 standard deviations higher than those for students in discordant pairs. These results show that large-scale reading improvements are achievable when classroom instruction is strengthened, and language-of-instruction policies account for teacher–student language concordance, not just school- or district-level assignments.