Abstract
<jats:title>Abstract</jats:title> <jats:p>As a cognitive theory of second language acquisition (SLA), generative SLA describes and explains the system of implicit second language (L2) knowledge as represented in the mind/brain of the learner. The logical problem of second language acquisition has powered the approach since the 1980s. It was noticed that, just like children acquiring their mother tongue, L2 learners also acquire linguistic knowledge that does not appear to come directly from language exposure. Since the input can be uneven, inconsistent, and unreliable, it frequently underrepresents the knowledge L2 learners ultimately acquire. However, the opposite is true too: sometimes the input is abundant, but the property is still difficult to acquire. The contention of generative SLA is that acquisition processes are streamlined by innate and domain‐specific linguistic knowledge. As with children acquiring their mother tongue, the SLA process is not instantaneous. Unfolding over time, transitional stages occur along a complex developmental continuum. Generative SLA conceptualizes these stages as step changes in interlanguage development. This entry describes how these step changes happen, and what they depend on. It also defines learning mechanisms and acquisition by processing.</jats:p>