Advocacy is acting with or on behalf of people with Down syndrome to resolve an issue, obtain needed support or promote a change in practices or policies. Advocacy is essential for promoting and protecting the civil and human rights of people with Down syndrome and for establishing, maintaining or improving their quality of life.

Individuals and organisations can be advocates for people with Down syndrome. DSi works with advocates in countries around the world to share knowledge and to offer information, advice and support, with the ultimate aim of improving quality of life for people with Down syndrome worldwide and promoting their inherent right to be accepted and included as valued and equal members of their communities.