Pegi Young, a late-blossoming folk-rock musician who was a founder of a school for children with severe physical and speech impairments, like her son from her marriage to the singer-songwriter Neil Young, a performer at its many star-studded benefit concerts, died on Tuesday in Mountain View, Calif. She was 66.

Her brother Paul Morton said the cause was cancer.

By the early 1980s, Ms. Young had grown frustrated with the special education programs available for her son, Ben, who was born with cerebral palsy in 1978. She began thinking about starting a school to better address his needs and those of other children who had largely lost the ability to speak.

That inspiration led in 1987 to the Bridge School, an innovative institution in Hillsborough, Calif., that has since achieved global reach. Ms. Young founded it with the speech and language pathologist Marilyn Buzolich and Jim Forderer, who had adopted many special-needs children.

At the school, about 17 miles south of San Francisco, children from ages 3 to 12 use augmentative and alternative communication techniques, including speech generators and manual communication boards, to help them articulate their thoughts and prepare to complete their educations in their local school districts.