Eunice Kennedy Shriver, 1921-2009 (PHOTOS)

BOSTON - Eunice Kennedy Shriver, the presidential sister who founded the Special Olympics and helped demonstrate that the mentally disabled can triumph on the field of competition and lead rich and productive lives outside the walls of institutions, died Tuesday at age 88.

Shriver had suffered a series of strokes in recent years and died at a hospital on Cape Cod in the company of her husband, her five children and her 19 grandchildren, her family said.

"She understood deeply the lesson our mother and father taught us: Much is expected of those to whom much has been given," said her sole surviving brother, Sen. Edward Kennedy, who is battling a brain tumor.

She was also the sister of President John F. Kennedy and Sen. Robert F. Kennedy; the wife of 1972 vice presidential candidate R. Sargent Shriver; the mother of former NBC newswoman Maria Shriver; and the mother-in-law of California Gov. Arnold Schwarzenegger.