This study investigated whether second language (L2) speakers' morphosyntactic pattern learning was predicted by their statistical learning and working memory abilities. Across three experiments, Thai English as a Foreign Language (EFL) university students (N = 140) were exposed to either the transitive construction in Esperanto (e.g., "tauro batas cevalon," "bull hits horse") or the nonprototypical English double-object dative construction (e.g., "John built the table a leg"). They also completed an aural test of statistical learning and a spoken backward digit-span test of working memory. In Experiment 1, only statistical learning was predictive of Esperanto pattern learning. Experiment 2 targeted pattern learning of the English nonprototypical double-object dative construction. Although working memory was associated with performance in the exposure phase, only statistical learning predicted test performance, as in Experiment 1. Finally, Experiment 3 served as a control condition in which participants were exposed to prototypical datives only during the exposure phase. This experiment showed that neither statistical learning nor working memory were associated with exposure or test performance. The findings are discussed in terms of the engagement of statistical learning and working memory during L2 pattern learning.