Adults with disabilities are 57% less physically active than individuals without disabilities and two times as likely to be obese. With obesity, adults with disabilities also face increased risk of comorbid disabilities stemming from obesity. The purpose of this theoretical case study was to identify key behavioral change theories which may be utilized to increase physical activity levels in adults with intellectual disabilities. The Self-Efficacy Theory and Self-Determination Theory both present constructs for understanding behavior change, and many of these constructs are interrelated which strongly suggests many behavioral change theories identify internal barriers for change. With theoretical case studies, these theories are examined within the context of adapted physical activity to depict how the Self-Efficacy Theory and Self-Determination Theory could be utilized to increase physical activity in individuals with intellectual disabilities.