This study examined the relationship between fifth-grade students' out-ofschool reading habits and measures of their reading comprehension and writing abilities. The sample was composed of forty-two students attending an urban school in Northeastern Massachusetts. Each morning, for fifteen consecutive weeks, students recorded an approximation of the number of minutes they spent on designated out-of-school activities for the previous evening. The total amount of minutes they spent reading was recorded on an evening activity-log and the mean amount of nightly reading volume, per student, was calculated. Student reading comprehension ability was measured by percentile scores on two standardized reading assessments. Students produced written responses in a weekly journal, and these were analyzed by way of two qualitative writing rubrics. A Least Squares Regression model was adopted for the analysis of outcome variables. The regression mode Is explicitly sought to investigate Stanovich's Matthew effects theory (2000), where student reading volume operated as the predictor variable. Results confirmed the study's research hypothesis. Student reading volume provided a correlation coefficient of r = .37 for reading comprehension and r = 0.61 for writing achievement. Moreover, all regression model results proved to be significant at a p = 0.05 level. Student reading volume proved to be a significant predictor for both reading and writing outcomes. The findings of this study support the overarching argument of the Matthew effects theory. Students who read a great deal outperformed their peers on measures of both reading comprehension and writing ability. This is because the increased amount of print exposure they experienced resulted in an expansion of their cognitive and linguistic knowledge base. In turn, this increased knowledge base reciprocally affected literacy outcomes. The educational implications of the study are that classroom practices which encourage student reading habits, both inside and outside of the classroom, are critical for all aspects of student literacy development. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]