Previous research showed that motivation influences writing in school settings (Hidi & Boscolo, 2006), but further empirical research is needed to understand how motivation influences specific writing tasks (Bruning & Horn, 2000; Haswell, 2006). This study addresses that gap in research by investigating how the motivational construct of learning goal orientations (Elliott & Dweck, 1988, 2005) mediates undergraduate students' revising of a research paper in a first-year composition class. The learning goal orientations framework poses two orientations: performance goal orientation in which students are motivated by appearing successful or avoiding appearing unsuccessful, and mastery goal orientation in which students are motivated by a desire to learn and understand concepts and skills. Using this framework, a mixed-methods study was conducted in one first-year composition class to uncover the relationship of revising practices and learning goal orientations. First, a class of twenty-two first-year composition students was surveyed to determine their learning goals using a modified version of the Patterns of Adapted Learning Scales (Midgley et al., 2000). Next, eight focus students--four scoring higher in the mastery orientation and four scoring higher in the performance orientation--were identified. Students were interviewed twice at two different time points during their research paper, and the researcher collected three subsequent drafts from each student. Triangulation of coded data revealed that revising practices were mediated by learning goal orientations. Mastery students made more changes between each draft and were more likely to make more significant changes including adding and deleting text at the sentence level as well as reorganizing substantial portions of the text. Interviews showed that performance goal-oriented students were motivated by performing smart and mastery goal-orientated students anticipated more revising. Surveys and interviews revealed that students with one stronger goal orientation simultaneously held the other goal orientation, but one took the foreground, and the other, the background. Implications for teaching are discussed. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]