This article introduces the lexical facility construct, an approach that characterizes vocabulary size and processing skill dimensions as complementary indices of second language (L2) vocabulary skill that, when combined, provide a more sensitive measure of individual differences in L2 vocabulary skill than vocabulary size alone. Lexical facility is described here as a vocabulary skill construct and a measurement construct. Theoretical and methodological issues arising from the proposal are discussed.

This paper begins by reviewing generative-based research from the past ten years. It will highlight some of the key findings and methodological tools from sentence processing research (e.g., Juffs & Rodríguez, 2014) and morphological processing (e.g., Clahsen et al, 2010; Cunnings, 2016; Diependale et al., 2011). Based on these findings, I will suggest that many questions that have concerned formal SLA (‘access to UG’, issues regarding ‘shallow’ processing and morphological ‘insensitivity’) are being resolved in favor of a view that, given time and exposure, adult L2 learners demonstrate knowledge that approaches (bilingual) ‘native speakers’. However, I argue that to remain relevant to a broader audience o f applied linguists, L2 research based on linguistic theory should account not just for knowledge of constraints on language, but also for what students comprehend and produce in over time in instructed contexts. Based on data collected in the English Language Institute at Pitt, I will make the case that corpus-based research that is informed by (formal) linguistics is necessary in a field that is increasingly dominated by scholars who see input frequency and saliency as the sole determining factors in acquisition. I will discuss studies from lexical, phonological, and morpho-syntactic development from students who have studied in an intensive English program over three semesters and show that the level of detail that a careful linguistic analysis provides is one that is useful to SLA research and language educators alike.

The role of instruction in second language (L2) acquisition has been investigated extensively over the past years (Norris & Ortega, 2000; Spada & Tomita, 2010). Yet it is only recently that applying L2 research findings in the generative framework to the classroom context has become a topic of interest (Whong, Gil, & Marsden, 2013; Whong, Marsden, & Gil, 2013). Focusing on the change in a learner's grammatical knowledge, this article reviews empirical findings on the unaccusative vs. unergative distinction among intransitive verbs and adjective ordering in prenominal modification in English. It will be argued that explicit instruction can facilitate second language development in these areas where, for example, learners have difficulty detecting overpassivization errors with unaccusatives (e.g., the airplane was arrived at the airport) or identifying the correct adjective ordering (e.g., a small square house, and not a square small house).