Since Sinclair (1991) concretized the possibilities of processing and analyzing large quantities of text data through corpus linguistic techniques, the applications of corpus linguistic approaches employing authentic language data and empirical evidence have been widely accepted in language teaching and research. As the applications of corpus linguistics develop, the range of corpus-based language learning has widened the perspectives in second and foreign language education for teaching vocabulary, grammar, reading, and writing. At the same time, corpus-based discourse analysis of written texts has been developed by using quantitative and qualitative evidence from corpus-linguistic approaches. The purpose of the current research is to explore the effects of corpus-based language learning in productive ESL vocabulary knowledge by analyzing the learners' writing samples and attitudes. Twenty-one international undergraduate students at a large Midwestern American public university were recruited and randomly assigned to an experimental group of concordancer (n=10) and a control group of thesaurus (n=11) for comparisons. Participants did seven writing samples each over an extended period of time using either the concordancer or the thesaurus to augment their writing. The samples were analyzed through corpus linguistic analysis to examine for changes in writing quality. Survey data were also analyzed to investigate the ESL writers' attitudes toward the corpus-based vocabulary reference tool. The results indicate that there were recognizable differences in the ESL writing quality between the groups. Although the study found that there was no statistically significant difference in lexical diversity of writing between the groups, there were significant differences in that the concordancer group gained more grammatical knowledge than the thesaurus group (p less than 0.05). The pre- and post-questionnaire results revealed that the ESL writers' attitudes toward the concordancer became negative, however. Unlike other similar studies, the current research sheds light on the effects of corpus-based learning in productive vocabulary knowledge by analyzing ESL writing samples and the learners' attitudes through quantitative and qualitative data that were gathered from a longitudinal voluntary-based quasi-experimental research design. The results indicated both positive and negative aspects of employing corpus-based language learning in ESL/EFL classrooms, which can be used as inputs to improve the approach. The conclusion also discusses the implication of the findings in corpus-based language teaching in classroom. [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.]