Extensive evidence indicates that oral language skills at school entry predict later reading development among monolingual children. It is not clear if the effect is the same for bilingually developing children and whether their oral skills in one language can transfer to reading comprehension in the other. The current longitudinal study followed 72 Spanish-English bilingual children (42 girls, 30 boys) and examined the extent to which early oral language proficiency in English and in Spanish were related to later reading comprehension development within- and across-languages. Multilevel models revealed significant within-language relations between oral language skills at 5 years and reading comprehension growth from 6 to 8 years in both English and Spanish. Additionally, English oral skill predicted Spanish reading comprehension, whereas Spanish oral skill was unrelated to English reading comprehension. Theoretical and practical implications of the findings are discussed.