Computers and mobile electronic devices in college and university learning environments present opportunity and risk. Paradoxically, such devices can add unprecedented value to the learning process while simultaneously presenting the risk of causing or exacerbating stress. College and university student populations have historically displayed high stress levels. Given this confluence of technology and stress with college and university students, understanding and mitigating stress related to computer and mobile device use is a worthwhile endeavor. Breathing activities are potential means of mitigating stress, including stress related to activities performed on computers and electronic devices. Some breathing activities have long histories of being used for self-regulation, and such activities might be useful to college students for stress management. The author used a within-subject, repeated measures, quasi-experimental interrupted time-series design to investigate this topic. Ninety-six students from a state university completed an activity sequence comprised of periods of quiet sitting, computer-mediated Stroop color-word activities and breathing activities. The author randomly assigned participants to three groups: (a) breath counting, (b) abdominal breathing and (c) combined: both breath counting and abdominal breathing. Participants also completed surveys designed to gather information regarding their impressions of the breathing activities, the perceived subjective norms related to the importance of breathing activities to their peers, family and culture, as well as their stage of change for stress management, breath attention and abdominal breathing. Evidence from this study suggests all three breathing activities are equally effective in enabling students to manage stress caused by a computer-mediated task. This study builds upon a previously published work in progress (Brumback, 2017) and pilot study (Brumback, 2018). [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]