This study explored subprocesses of reading for 157 fifth grade Spanish-speaking English language learners (ELLs) by examining whether morphological awareness made a unique contribution to reading comprehension beyond a strong covariate-phonological decoding. The role of word reading and reading vocabulary as mediators of this relationship was also explored. Results showed that fourth grade morphological awareness did not make a significant unique direct effect on fifth grade reading comprehension, controlling for phonological decoding, word reading, and reading vocabulary. Fourth grade morphological awareness did, though, make a unique moderate total contribution to fifth grade reading comprehension with reading vocabulary, but not word reading, mediating the relationship when controlling for phonological decoding. In contrast, phonological decoding made a nonsignificant total contribution to reading comprehension with neither word reading nor reading vocabulary mediating the relationship when controlling for morphological awareness. Alternative models were also explored, showing the importance of including both predictors in a model of ELL reading comprehension, primarily to include the support of phonological decoding to word reading and the support of morphological awareness to reading comprehension via reading vocabulary. Results highlighted the importance of morphological awareness in facilitating reading comprehension via improving reading vocabulary knowledge, and also the potential of interventions involving morphological instruction to support reading achievement for Spanish-speaking ELLs.