This study compared variables related to reading ability in Grade 3 students learning English as a first language (L1) and second language (L2). The students learning English as an L2 came from diverse backgrounds, with different levels of bilingualism in Spanish and English or Portuguese and English before they entered school. Both within-group and between-group differences emerged in comparing Spanish children from two cohorts, and in comparing the Spanish group to the Portuguese and English groups. Models predicting reading comprehension found differences with respect to the contribution of receptive vocabulary, decoding, and print exposure in the L1 and L2 groups, depending on the L2 students' bilingual language status and language acquisition experiences. Additionally, print exposure was more highly related to comprehension in the lowest performing L2 groups. Implications and future directions are discussed.