Motivational variables, such as writing self-efficacy and writing attitudes, are not emphasized in writing frameworks for developing writers. The purpose of this research study was to extend the research literature on elementary-aged students' writing development by examining the potential mediational role of writing self-efficacy and writing attitudes between foundational academic skills (e.g., handwriting, spelling, and executive functioning/working memory skills) and written performance. Measures of spelling, handwriting, executive function/working memory skills, writing self-efficacy, writing attitudes, and written expression were administered to 140 third-grade and fifth-grade students. In this correlational research study, a parallel mediational analysis was conducted to examine whether writing self-efficacy and writing attitudes functioned as mediating variables between transcription skills (i.e., handwriting and spelling), executive functioning/working memory ability, and students' subsequent writing performance. Results demonstrated that neither writing self-efficacy or writing attitudes mediated the relationship between variables associated with students' writing development. Implications of this study and directions for future research of writing self-efficacy and writing attitudes within writing development 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]