The current research aims to predict L1 Papiamento and L2 Dutch reading comprehension development in 180 children in the upper primary grades (4–6) in a post-colonial Caribbean context from initial language of decoding instruction, cognitive and linguistic child characteristics, and linguistic transfer. Overall, children showed better reading comprehension proficiency in L1 as compared to L2 Dutch. Over the grades, strong autoregression effects in reading comprehension development in both languages were evidenced. Language of decoding instruction was found to predict L2 reading comprehension, but not L1 reading comprehension. The development of L2 reading comprehension showed better outcomes in the case of initial decoding instruction in L2. Word decoding, reading vocabulary, and grammar in respectively L1 and L2 were related to L1 and L2 reading comprehension in Grade 4, while L2 reading comprehension was additionally related to L2 basic oral vocabulary. Moreover, only reading vocabulary was related to L1 and L2 reading comprehension development across the grades. Finally, evidence of cross-linguistic interdependencies in the development of reading comprehension in L1 and L2 was found.