Lexis-based views of second or foreign language (L2) teaching place prime importance on the teaching of conventionalized multi-word lexical items, or unanalyzed chunks, as a useful mechanism for fostering learners' creative production of forms and their subsequent development of L2 competence. This pretest/posttest quasiexperimental study probed the use of teacher-designed multi-purpose instructional lexis software, dubbed LexisBOARD, on L2 learners' vocabulary achievement in an Iranian EFL (English as a foreign language) context. A cohort of 50 Iranian junior-high-school students participated in the main instructional phase of the study. Instruction on L2 lexical items (e.g., concordances, polywords, or formulaic sequences) was mainly given to the experimental group using LexisBOARD, which was designed to be user-friendly and attuned to learners' communicative and curricular needs. LexisBOARD offered further practice or feedback affordances through engaging students in lexical exercises (with word partnerships and collocations) for each unit and several quizzes for self-assessment. The control group was only taught using their mainstream EFL textbooks focusing on grammatical rules, discrete vocabulary items with fixed meanings, and reading texts, without any use of corpus-based activities. The results of the groups' vocabulary test scores indicate that the lexis group significantly outperformed the control group, pointing to the superiority of practicing and learning L2 vocabulary when lexical items are seen in larger, more holistic ways and, especially, when engaging and experimenting with lexis is scaffolded through computer affordances.