Margaret Joan Giannini (May 27, 1921 – November 22, 2021) was an American physician and a specialist in assistive technology and rehabilitation.

In 1950, after hearing the frustrations of her patients' families, she founded the Mental Retardation Institute, a multidisciplinary clinic to treat people with intellectual disabilities, including classrooms, dental care, and social work services.

[5] As the center's director, she raised funds, hired specialists, and oversaw research projects.

[9] Giannini appeared in medical videos including The Seattle Foot (1980), Audiology (1984),[10] and Environmental Medicine (1985).

[17] Giannini became director of the National Institute of Handicapped Research (now NIDRR) in 1980, appointed by Jimmy Carter.

[18] In 2018, she was the first recipient of the Award for Lifetime Achievement in Advancing Community Living, presented to her by Health and Human Services Secretary Alex Azar at an event marking the fortieth anniversary of the NIDILRR (formerly NIDRR).