Intellectual disability is a disability that occurs before age 18. People with this disability experience significant limitations in two main areas: 1) intellectual functioning and 2) adaptive behavior. These limitations are expressed in the person's conceptual, social and practical everyday living skills. A number of people with intellectual disability are mildly affected, making the disability difficult to recognize without visual cues. Intellectual disability is diagnosed through the use of standardized tests of intelligence and adaptive behavior. Individuals with intellectual disabilities who are provided appropriate personalized supports over a sustained period generally have improved life outcomes (AAIDD, 2011). In fact, many adults with intellectual disabilities can live independent, productive lives in the community with support from family, friends and agencies like The Arc. This informative guide provides information to parents, and community members on the following topics surrounding intellectual disabilities: (1) The number of people who have intellectual disabilities; (2) Definition of intelligence; (3) Adaptive behavior; (4) How having an intellectual disability can affect someone's life; (5) A definition of developmental disability, and comparison to intellectual disability; and (6) Ways community can support people in the community who have intellectual and developmental disability.