Data from the National Center for Education Statistics (2012) indicates that a large majority of students with disabilities continue to perform at basic proficiency or below in writing, which has serious implications for post-secondary academic endeavors and successful transition into the workforce (US Department of Labor, 2014; Bureau of Labor Statistics, 2017). Therefore, it is imperative to identify and implement effective writing interventions for this population of students. Self-Regulated Strategy Development (SRSD) has been widely researched in elementary and middle school settings, but more research needs to be conducted with high school students. This study aimed to examine the impact of SRSD on the argument writing of three high school students with mild disabilities using a multiple baseline research design in a secondary setting. The results of this research extend the existing body of evidence related to writing interventions for secondary students with disabilities who intend to pursue post-secondary education and inform possible directions for postsecondary writing interventions for students with disabilities.