It may be the least-publicized revolution of our time but the one whose impact ultimately reaches the furthest, affecting the way our buildings and buses are built, the way our schools are structured, the way our businesses conduct hiring and outfit their work stations. It’s the disability-rights movement, and “Lives Worth Living,” a Thursday “Independent Lens” on PBS, reconstructs how it emerged and eventually pushed through the Americans With Disabilities Act of 1990.

The film opens with images from the past that are chillingly grim, especially those from the Willowbrook State School for children with intellectual disabilities on Staten Island, a nightmarish place exposed by, among others, a young television reporter named Geraldo Rivera in 1972. (Recent headlines have made clear that, four decades later, such problems persist in some places.) “There was a belief,” Ann Ford, director of the Illinois chapter of the National Council on Independent Living, says bluntly, “that if you had a disability, you didn’t have any desire to live a life.”

It was the return of injured veterans from World War II that began to shake that assumption. The veterans, viewed as heroes, were not being written off, and those born with disabilities started to think that they shouldn’t be either. The filmmakers interview some of the central figures in the formation of the movement, who talk about learning from the feminist and civil rights causes. Oddly, buses were again important, as Bob Kafka of the group Adapt notes....