It is now well established that anticipation of up-coming input is a key characteristic of spoken language comprehension. Several mechanisms of predictive language processing have been proposed. The possible influence of mediating factors such as working memory and processing speed however has hardly been explored. We sought to find evidence for such an influence using an individual differences approach. 105 participants from 32 to 77 years of age received spoken instructions (e.g., "Kijk naar deCOM afgebeelde pianoCOM" - look at the displayed piano) while viewing four objects. Articles (Dutch “het” or “de”) were gender-marked such that the article agreed in gender only with the target. Participants could thus use gender information from the article to predict the upcoming target object. The average participant anticipated the target objects well in advance of the critical noun. Multiple regression analyses showed that working memory and processing speed had the largest mediating effects: Enhanced working memory abilities and faster processing speed supported anticipatory spoken language processing. These findings suggest that models of predictive language processing must take mediating factors such as working memory and processing speed into account. More generally, our results are consistent with the notion that working memory grounds language in space and time, linking linguistic and visual-spatial representations.