This study investigated the use of reflective portfolios in science as a means to provide students a medium to develop a repertoire of study and self-regulation strategies. These self-regulation strategies can be accessed and utilized by students to engage in independent study and help to manage workloads from multiple teachers. The use of a reflective portfolio addresses the theoretical framework laid out by Pintrich which organized regulatory processes according to four phases (a) planning, (b) self-monitoring, (c) control, and (d) evaluation. The reflective portfolio included student work samples, revisions of work, reflections, and goal statements. Construction of the portfolio gave students the opportunity to engage in a cyclical process of self-regulation facilitating an on-going assessment dialogue between themselves and their teacher. The focus of this study was a convenience sample of students from a public high school in a suburban community (population of 24,000) in the Northeast. The study used a quasi-experimental research design. Participants in the study included 158 (n = 158) students in a nonrandomized control-group, pretest-posttest design. Two different situations were compared; (a) reflective portfolio use and (b) no use of reflective portfolios. Research question 1 asked: Is there a significant difference in the self-regulatory skills of high school science students who produce reflective portfolios for their science assignments and those who do not? The Motivated Strategies for Learning Questionnaire (MSLQ) subscales of Metacognition Self-Regulation, Effort Regulation, Time and Study Environment, Rehearsal, Elaboration, and Organization were used to assess student self-regulatory skills. A multivariate analysis of variance (MANOVA) was applied where the six subscales served as the multiple dependent variables. The isolation of which specific self-regulatory learning strategies (Metacognition Self-Regulation, Effort Regulation, Time and Study Environment, Rehearsal, Elaboration, and Organization) were affected by reflective portfolio use in science was statistically insignificant. Research question 2 asked: Is there change over time in the Portfolio Rubric scores within the group of students who produce reflective portfolios? The student generated reflective portfolios produced in the treatment group were assessed using the Portfolio Rubric. Four one-way repeated measure analysis of variance (ANOVA) procedures were used to ascertain if the rubric scores varied depending on the time interval. Statistically significant gains in students' rubric scores over time suggest students do benefit from structured goal setting, revision, and reflection. The findings of this study support the use of reflective portfolios to provide students the necessary mastery goal orientation to reflect upon their current progress towards meeting their academic goals. Additionally, this study suggests reflective portfolio use allows students to consider behavioral changes necessary to meet their goals and provides a framework for a dialogue about self-regulation and performance between teachers and students. [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.]