The purpose of this quantitative, non-experimental, causal-comparative study is to determine if there is a difference in the writing motivation of students with attention-deficit/hyperactivity disorder (ADHD) and students without ADHD in online college composition I courses. The study of writing motivation in relation to ADHD in online college composition courses is significant as writing motivation is a crucial predictor of academic success and persistence. Data was collected from a population of approximately 1685 students enrolled in online college composition I at an accredited online university within a larger midwestern land-grant public university system. Using the Writing Motivation Questionnaire and the self-reported results of the covariate (Personal Writing Assessment score), students without ADHD were compared to students with ADHD to determine how writing motivation construct scores differed between the groups. The data was analyzed using a one-way analysis of covariance controlling for the effect of the covariate, and the results demonstrated that this sample of online college composition students with ADHD had lower levels of writing motivation, which correlated with lower previous writing abilities. Further discussion included the impact of ADHD on writing motivation, academic success, and the link to early assessment. The implications of the research suggest a need for accommodation. Limitations, such as the time constraints of the survey combined with the assessment, were also addressed, and recommendations for further research using essay writing as the covariate were made. [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.]