Second Language Instruction Does Make a Difference

A number of studies on second language (SL) instruction point to the hypothesis that instruction is effective, but determining the effect experimentally has been problematic. Overall, three difficulties with previous attempts to demonstrate a causal relationship between SL instruction and second language acquisition can be identified: (a) inappropriate or inadequate research design, (b) failure to operationalize or even to describe the instructional treatment, and (c) choice of SL assessment measures. This article presents the findings of a recent empirical study which (a) show that SL instruction is effective; (b) show that attention to form, either via detailed analysis of structure or highlighting of target language (TL) structures in context, promotes acquisition of interlanguage (IL) grammar, but that only the latter comes hand-in-hand with comprehension of input; and (c) replicate earlier findings suggesting an important role for markedness theory in instructed IL development.