This dissertation examined the status of data-based research in applied linguistics through an analysis of published research studies in nine peer-reviewed applied linguistics journals ("Applied Language Learning, The Canadian Modern Language Review / La Revue canadienne des langues vivantes, Current Issues in Language Planning, Dialog on Language Instruction, Language Learning, Language Teaching Research, Language Testing, The Modern Language Journal, TESOL Quarterly") recommended by the American Association for Applied Linguistics (AAAL), during a particular seven-year period (2002-2008), so as to determine the research methods used. It analyzed the implementation of statistical procedures in those studies that use quantitative research methodology, and classified qualitative studies according to research methodology. Mixed studies were categorized according to research methodology and statistical procedures. The survey of the data-based studies published in all nine journals from 2002-2008 revealed that of the 636 research articles, 406 (64%) used quantitative research design, 177 (28%) used qualitative research design, and 53 (8%) used mixed research design. Analysis of variance (ANOVA) (used in 42% of the studies), t-test (in 32%), and Pearson product-moment correlation coefficient (in 28%) were the most frequently used statistical procedures employed in the quantitative studies. Case studies (in 25% of the articles) and interview (in 21%) were the most frequently used research methodologies in the articles that used qualitative research design. The comparison based on the three journals ("TESOL Quarterly, Language Learning and The Modern Language Journal") that are surveyed in this study and in Lazaraton's study (2005) revealed an evident increase of qualitative and mixed studies and the decrease of quantitative studies in 2002-2008, as compared to the studies published in the same journals in 1991-2001. [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.]