Recent theoretical advances viewing language aptitude as multifaceted have led to accumulated evidence on certain constructs beyond the specifications of traditional aptitude tests. In this chapter, we consider the potential role of implicit statistical learning (ISL) mechanisms in second language acquisition (SLA). First, terminological and conceptual issues are examined with the goal of clarifying the processes and knowledge that ISL tasks are claimed to involve. Second, we consider justifications for research into the potential link between ISL and SLA by reviewing the argument for a default implicit processing mode in adult L2 learning. Third, we provide a synthesis of studies assessing the link between ISL and L2 outcomes based on the following research questions: (1) Which studies have examined the association between ISL tasks and L2 outcomes and what are their characteristics? (2) Which measures have been used to investigate the construct of ISL? And (3) What are the accumulated findings of the studies? The overall results of a Bayesian meta-analysis confirmed a positive, albeit weak, link between ISL and SLA (r =.13, [.05,.22]). Moderator analyses and a critical review of ISL tasks suggest avenues for future research.