While a bilingual advantage is widely observed in some word learning paradigms, its existence in statistical word learning, where each word learning situation by itself is ambiguous, remains debated. Some research in this field suggests that bilinguals have a general advantage over monolinguals, while other studies show differences only under specific conditions or no differences at all. Thus, as part of a registered report, our study investigated statistical word learning using the Cross-Situational Statistical Learning paradigm in two adult groups: English-German bilinguals and English monolinguals (overall N = 200). Participants learned single (1:1—one word maps onto one object) and multiple mappings (1:2—one word maps onto two objects). We predicted, consistent with the literature, that acquiring 1:1 than 1:2 mappings would be easier, and we confirmed this hypothesis. We also predicted that bilinguals would outperform monolinguals for 1:2 mappings, consistent with a specific bilingual advantage (i.e., bilinguals’ higher familiarity with multiple mappings may result in a learning advantage for these mappings only). Contrary to our expectations, we found a general monolingual word learning advantage without any specificity for mapping types. Furthermore, we measured learning continuously and analysed trial-by-trial behaviour to understand fine-grained learning differences across language groups. Participants were indeed using their previous knowledge (of the target and foil objects) to inform their behaviour on a current trial; however, no differences in learning patterns emerged between groups. Overall, our findings challenge the assumption that bilingual advantages extend to statistical word learning, suggesting a monolingual advantage in this context instead.