“I went into television because I hated it so,” Rogers once said in an interview with CNN. “I thought there was some way of using this fabulous instrument to be of nurture to those who would watch and listen.” While attending the seminary, Rogers pursued a career in the then-nascent TV industry, getting a job at NBC in 1951. Unhappy with the network’s reliance on sponsorship and advertising, he moved to WQED in Pittsburgh, a public station where he’d eventually oversee the U.S. launch of his self-titled show in 1968.

In television, Rogers saw an instrument with amazing, or terrible, potential. It was a form of mass communication unlike any other, one that would have particular potency with young, impressionable viewers with a weaker grasp of the lines between fiction and reality. As someone who had considered working in the church, Rogers understood better than most the value of a pulpit; he was thus all the more horrified by the way television was mostly used to sell, rather than teach, things.

Much of Neville’s film exists to chart the ways in which Mister Rogers’ Neighborhood was revolutionary. The program’s first week of episodes alluded to the Vietnam War, playing the conflict out through an allegory involving the show’s puppet characters (including the bossy King Friday, who builds a barbed-wire barrier around his castle). The character Officer Clemmons (played by the actor and singer François Clemmons) was one of the first African Americans to have a regular role on children’s television, and Rogers would include pointed scenes, like one where the two washed their feet in a tub together as a way of challenging segregated swimming pools.

Neville makes some effort to include Rogers’s shortcomings as well, like the fact that the host wouldn’t let Clemmons publicly acknowledge his homosexuality in the 1970s, knowing the show’s sponsors would disapprove. But the film, by and large, endorses Rogers’s importance to the world of public television, with one section focusing on his iconic testimony to Congress about the value of funding PBS (which helped sway at least one crucial senator’s opinion). “I’m very much concerned … about what’s being delivered to our children in this country,” Rogers testified.

His concerns never faded. The show took a hiatus from 1976 to 1979 but returned partly because Rogers was so disturbed by news reports of children injuring themselves while pretending to be superheroes. He worked to establish clear lines between fantasy and reality, underlining the pretend nature of his own show’s “Neighborhood of Make-Believe” (populated with puppets that he voiced), and encouraging his young viewers to consider the fictional elements of the things they watched.

Won’t You Be My Neighbor? lays out the arc of Rogers’s career thoughtfully, but it’s most effective as a document of his basic beliefs about the power of art. It explores how Rogers kept Mister Rogers’ Neighborhood from capitulating to many emerging trends in kids’ entertainment (other programs were often packed with energy and violence, or geared toward selling toys). Rogers kept his show steeped in routine and patience: There was his famous opening routine (changing into a sweater, putting on comfortable shoes) as well as segments that bordered on abstract (like one where he pointed the camera at an egg timer that was silently counting down, to help kids understand how long a minute actually was).