The Arc of the South Shore is guided by a mission to provide the highest quality services and advocacy for children and adults with mental retardation, and cognitive, physical, and developmental disabilities. The Arc of the South Shore is a family oriented, community-based non-profit agency, which believes that all individuals have the right to participate fully in their community.

The Arc of the South Shore holds the principle that communities have a responsibility to accept and support their members who face developmental challenges, and to help them exercise their skills and abilities. In practice, The Arc of the South Shore strives to provide services that fully integrate individuals into the life of the community, that are responsive to the full range of individual, family and community needs, and that incorporate effective systems of family support.

The Arc of the South Shore also undertakes a broad range of legislative advocacy, information and referral, parent networking, community education, consultation and outreach activities. These activities are designed to increase public awareness of the needs of persons with developmental disabilities and the availability and quality of resources to serve them. The Arc of the South Shore has been providing services since 1951.