In the present study, we compared the extent to which linguistic comprehension (vocabulary and listening comprehension) and word reading explain reading comprehension differentially for English learners (ELs) and non-ELs with reading difficulties. We also investigated whether different mechanisms of reading comprehension failure exist for each group. Using the simple view of reading as our framework, we tested a model in which vocabulary exerts a direct effect on reading comprehension and indirect effects through listening comprehension and word reading. Results from a multigroup structural equation model with a sample of 440 struggling fourth-grade readers (n = 229 for ELs; n = 211 for non-ELs) demonstrated both similarities and differences in the sources and mechanisms of reading comprehension difficulties for ELs and non-ELs with reading problems. Word reading was an important source of reading comprehension difficulty for both groups. For non-ELs, the effect of word reading was larger than the effects of linguistic comprehension (vocabulary and listening comprehension combined); however, for ELs, the effects of linguistic comprehension were greater than the effect of word reading. Vocabulary had indirect effects via both listening comprehension and word reading for ELs, but it demonstrated a direct effect on reading comprehension for non-ELs. These results suggest that developing a range of linguistic comprehension skills (e.g., word-level and sentence-level language skills) may be important for ELs with reading comprehension difficulties in the upper-elementary grades. Educational Impact and Implications Statement: The results from the present study provide evidence that word reading and linguistic comprehension contribute to reading comprehension for English learners (ELs) and non-ELs with reading difficulties in different ways. Although both word reading and linguistic comprehension were associated with reading comprehension for both groups, the relative contribution of these skills differed. Whereas limited word reading skill was a major source of reading comprehension difficulties in non-ELs, linguistic comprehension contributed to reading comprehension more than word reading in ELs. Moreover, the mechanism by which vocabulary was associated with reading comprehension differed for ELs and non-ELs. Specifically, vocabulary had a direct relation to reading comprehension for ELs and non-ELs, but it was completely mediated by listening comprehension for ELs only.