The aim of this study was to parse types of self-regulation and understand their relations with writing quality. Various skills within self-regulation are indirectly related to written expression. This is because of their influence on self-regulation processes, such as planning, within the writing process. However, studies have not yet clarified how self-regulation and its subskills influence writing quality. Earlier empirical models did not directly measure self-regulation and planning in the mediation model that is currently regarded as the most comprehensive model of writing to-date. This study sought to explore the specific mediational path between types of self-regulation, planning, and writing quality, so that a case for using specific effective intervention strategies within self-regulated strategy development may be supported. A teacher rating scale, the BRIEF-2, was used to conduct factor analytic, correlational, regression, and mediation analyses with planning and writing quality in a sample of Grade 4 and Grade 5 students (n = 161). [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.]