The aim of the present study is to determine the within-language and across-language longitudinal development of phonological processing skills (phonological awareness, phonological working memory and rapid automatised naming) and literacy (letter-sound knowledge, word recognition, text reading, reading comprehension, spelling) skills of emergent bilingual speakers of two closely related African languages (isiXhosa and isiZulu), and English from Grades 1 to 3. To meet this aim, parallel (African language – English) phonological processing assessments will be designed for this study. Additionally, the observed phonological processing and literacy developmental trajectories will be interpreted in light of theories of phonological processing development and linguistic transfer.