In this longitudinal study, we examined the relationship between primary grade (K-2) Spanish and English language- and word-based skills and later English reading comprehension (RC) outcomes (Grades 5 and 8) among children (n = 148) from immigrant, Spanish-speaking, low-income homes in English instructional contexts since kindergarten entry. As expected, early skills, especially those in English, contributed to later RC outcomes. Most uniquely, we identified a developmental shift in the contribution of language- and word-based skills on students' RC outcomes. Specifically, word-based skills were consistently predictive of Grade 5 RC outcomes, whereas the contribution of language-based skills emerged for Grade 8 RC outcomes. Finally, we also found that the relationship between early skills and later RC outcomes varied depending on students' RC levels. These results underscore the increasingly important role that early language-based skills play for later English reading comprehension outcomes, and we discuss theoretical and practical implications of this work.