In recent years, L2 researchers from the sociocultural and cognitive linguistic perspectives have emphasized the importance of properly organized explicit and in-depth grammar instruction for second or foreign language learning. Such instruction is believed to lead learners to systematic understanding of the target features faster and more efficiently. This study reports on a classroom implementation of innovative language lessons on English phrasal verbs in order to support this view. The design of the lessons is based on Vygotskyan pedagogical theory, concept-based instruction, the key concepts of which are materialization, verbalization and internalization (Vygotsky, 1981, 1983, Gal'perin, 1969). The content of the lessons comes from cognitive linguistic notions, in particular conceptual metaphor (Lakoff & Johnson, 1980) and image schema (Johnson, 1987). Class instruction was designed to highlight the systematicity of the semantics of phrasal verbs and to reinforce learners' conceptual understanding with various learning activities. Six 50 minute class sessions introduced students to the semantics of three particles, out, up and over. A total of 23 international teaching assistants were enrolled in the course taught at a North American research university. Participants' performances in various tasks including in-class tests and homework assignments were analyzed quantitatively and qualitatively to investigate learner development. The quantitative data consists of multiple-choice tests that assessed whether students were capable of choosing an appropriate phrasal verb in a series of varied sentential contexts. The qualitative datasets were collected from following tasks: verbalizations, definitions and two explanation tasks. The tasks were not only designed to reveal effect of instruction, but also to reinforce the learning process. The analyses of the various data sets showed that CBI enhanced understanding for the majority of students meanings of phrasal verbs in a more systematic manner and to properly externalize that understanding. Their performance significantly improved and the guessing rate decreased. Transfer to new items and particles also occurred. In addition, their explanations became semantically rich and image-oriented. Their explanations indicated that the SCOBAs (Schemas for the Orienting Basis of Action) developed to accompany the explanation of the metaphorical properties of phrasal verbs were clearly instrumental for understanding the motivated nature of particle use. The overall encouraging results point to the need for meaning-oriented grammar instruction that draws learners' attention to the conceptual bases of grammatical features including seemingly arbitrary phrasal verbs and other idiomatic expressions. This type of instruction is more advantageous in that it can promote conceptual understanding, theoretical thinking and practical application. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]