After only four years of operation, On December 12, 2002, the Commission on Membership and Evaluation voted unanimously to grant The Stanwich School unconditional accreditation by the Connecticut Association of Independent Schools.  Accreditation signifies that The Stanwich School has demonstrated its excellence in every aspect of its program, including delivery of its unique mission. The School is a member of CAIS and, correspondingly, a member of the National Association of Independent Schools. 

The Stanwich School is a founding member of REACH Prep, an organization that prepares low income, minority students for enrollment in area independent schools.