In this study, physiological and psychological outcomes of an 8-week moderate to vigorous aerobic exercise program (Zumba®) for adults with intellectual and developmental disabilities (IDD) were examined. Forty-six participants were randomly assigned to the experimental group ( n = 24) or control group (n = 22). The experimental group participated in Zumba® for 8 weeks, 3 days per week, along with completing exercise rating scales and fitness tests. Outcome measures included agility, endurance, rate of perceived exertion (RPE), exercise motivation, and exercise self-efficacy. Agility, endurance, and RPE were measured by three fitness tests; Timed Up and Go (TUG) test, the Six-Minute Walk Test (6MWT), and Modified Borg Dyspnoea (MBD). Physiological outcomes were measured before the intervention (pretest), 4 weeks during the intervention, and after the intervention (posttest). The experimental group completed a follow-up of all three fitness tests 2 weeks after the removal of the intervention. A paired t test assessed the continuous measures within each group. Exercise motivation and exercise self-efficacy were measured by two exercise scales: the Exercise Motivations Inventory (2nd Ed) (EMI-2) and the Exercise Self-Efficacy Scale (ESES). Participants were able to respond on a 5-point Likert scale: 0 = "not at all true for me" to 5 = "very true for me." The ESES contained 10 items that addressed an individual's belief to engage in exercise based on natural environmental conditions. Participants were able to respond on a 4-point Likert scale: 1 = "not at all true" to 4 = "always true." Both scales were administered using the university software Qualtrics®. Participants indicated on a touch screen computerized device (i.e., cellular device or iPad®) their responses by touching the device with their finger. Psychological outcomes were measured before the intervention (pretest), 4 weeks during the intervention, and after the intervention (posttest). An independent t test assessed the differences between the experimental and the control group. Results indicated that there was a significant difference between the experimental and the control group on the physiological outcomes, but not on the psychological outcomes. Although both groups' mean scores increased during each phase of the intervention, the scores of the experimental group indicated a significant difference compared to the control group. Analysis of data, implications, and recommendations for future research 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.]