We examined the relationship between inference making, vocabulary knowledge, and verbal working memory on children's reading comprehension in 62 6th graders (aged 12). The effect of vocabulary knowledge on reading comprehension was predicted to be partly mediated by inference making for two reasons: Inference making often taps the semantic relations among words, and the precise word meanings in texts are selected by readers on the basis of context. All independent variables were significantly and moderately correlated with reading comprehension. In support of our prediction, the link between vocabulary knowledge and reading comprehension was significantly mediated by inference making even when verbal working memory was controlled. An alternative mediation hypothesis (vocabulary as a mediator of the effect of inference making on comprehension) was not supported by the data. The study replicates and extends the findings of earlier work (Cromley & Azevedo, 2007; Segers & Verhoeven, 2016; Ahmed et al., 2016).