In the current era of standards-based education, student self-assessment stands alone in its promise of improved student motivation and engagement, and learning. Correctly implemented, student self-assessment can promote intrinsic motivation, internally controlled effort, a mastery goal orientation, and more meaningful learning. Its powerful impact on student performance--in both classroom assessments and large-scale accountability assessments--empowers students to guide their own learning and internalize the criteria for judging success. In this article, the authors define student self-assessment and its importance in influencing student motivation and learning. The authors begin with a detailed definition of self-assessment, then review pertinent theoretical and research literature that supports the positive impact of student self-assessment in the classroom. The authors intention is to show that, based on both theoretical and applied research and theory, self-assessment works, and that by applying a set of practical steps teachers can facilitate this kind of assessment and reap the benefits. (Contains 2 figures.)