Indigo Girls have been going strong for over 40 years now, and maybe the key to their resilience is that they never were cool. Often, they got it worse: Even at their commercial peak in the 1980s and ’90s, Amy Ray and Emily Saliers were routinely mocked for being too earnest, too poetic, too folky, too lesbian. Back then, being labeled a female, gay singer-songwriter was an artistic and commercial curse, as Ray recalls in “It’s Only Life After All,” a smart, compelling new documentary.

The director, Alexandria Bombach, greatly benefited from Ray’s archivist instincts: The musician has held on to decades’ worth of artifacts and opened up her vault — 1981 rehearsals, recorded on cassette when Ray and Saliers were in their teens, are startlingly crisp documents of a budding chemistry, for example.

From this clay Bombach has sculpted an affecting portrait of two women who have stuck to their beliefs and, just as important, their loyalty to each other. Existing fans will be mesmerized, but non-fans like me should also get a kick out of “It’s Only Life After All.” The film is especially good about contextualizing the band’s emergence in the midst of condescension (at best) from the mainstream media — their dramatic, and very funny, reading of a withering 1989 review in The New York Times is a highlight — along with their personal struggles and steadfast political engagement for causes, including the Indigenous-led organization Honor the Earth.

Now that the band is experiencing a cultural moment — its hit “Closer to Fine” was prominently featured in “Barbie,” and an indie jukebox musical movie set to their songs, “Glitter & Doom,” came out last month — it is delightful to see them have the last laugh.

It’s Only Life After All
Not rated. Running time: 2 hours 3 minutes. In theaters.