Foreign language (FL) knowledge has been shown to contribute significantly to FL reading performance. Studies have contrasted the contribution of FL vocabulary and syntactic knowledge, following a dichotomous view of these components, producing mixed results. Despite the increasingly recognized formulaic nature of language, the contribution made by phraseological knowledge to reading ability has not been investigated systematically. This study examines the impact of a broader construct definition of linguistic knowledge--which includes a phraseological component--in explaining variance in reading performances. Test scores of 418 learners of English as a foreign language (EFL) were modeled in a structural equation model, showing that a phraseological knowledge measure outperformed traditional syntactic and vocabulary measures in predicting reading comprehension variance. Additional insights into the role of phraseological knowledge were gained through verbal protocol analysis of 15 EFL learners answering reading comprehension items that targeted the understanding of phrasal expressions within written context. The findings hint at an underestimated, but critical, role of phraseological knowledge in FL reading, and are relevant to both the assessment and the teaching of EFL ability.