Worldwide, the community transition process away from institutions has increased in the past 30–50 years among persons with severe intellectual and developmental disabilities. This process, also known as “deinstitutionalization”, could potentially impact problem behaviors and communication. This study examined the impacts of community transitions on behavioural and communication outcomes in Canadians with intellectual and developmental disabilities. Data were collected using the Comprehensive Health Assessment Program and medical chart reviews. Descriptive, aggregate-level, and individual-level analyses were conducted for 32 adults who transitioned to community living. Descriptive analyses and the McNemar Chi-Square Test were conducted. Following community transitions, the study group experienced a significant decrease in problem behaviours and changes in communication. The study findings suggest that deinstitutionalization could provide effective strategies for addressing problem behaviors and fostering improvements in communication, promoting the well-being and quality of life of persons with intellectual and developmental disabilities.