Abstract:Abstract: The Interface Hypothesis and the acquisition of interface knowledge have been the research focus of the generative approach to second language acquisition in recent years. The hypothesis effectively explains the L2ers’ general failure to achieve target-like interlanguage from the perspective of language processing. The Interface Hypothesis and the concept of interface are introduced first in this article. The previous empirical studies are then reviewed, and some misconceptions about and the problems with the hypothesis are spelt out. Finally, the fields where the Interface Hypothesis is applicable are further explored.