Sly Stone performing at the Harlem Cultural Festival in 1969, featured in the documentary “Summer of Soul.” (Searchlight Pictures)
Chief film critic

Rating:  (4 stars)

Ahmir “Questlove” Thompson makes a spellbinding directing debut with “Summer of Soul (. . . Or, When the Revolution Could Not be Televised),” a revelatory documentary that exhilarates and dismays in almost equal measure.

In 1969, New York producer and impresario Tony Lawrence masterminded the Harlem Cultural Festival, a summer-long live music series that would be held over six weekends in Upper Manhattan’s Mount Morris Park (now also known as Marcus Garvey Park). Sometimes called the “Black Woodstock,” the concerts ultimately drew more than 300,000 people to see acts ranging from the Staple Singers to Hugh Masekela; from Gladys Knight & the Pips to Sly and the Family Stone; and from Nina Simone to the 5th Dimension.

With its jaw-dropping lineup and epochal timing on the heels of one of the most tumultuous years in American history, the Harlem Cultural Festival was important on myriad levels, material and symbolic. But although it was filmed for a local news station, that footage sat untouched for 50 years before being discovered and given to Roots co-founder Thompson as the raw material for his first directorial effort. What he has created with “Summer of Soul” transcends a mere chronicle of a legendary concert — which, frankly, would have been entertaining enough. Instead, he pulls the lens back to examine an event whose artistic and generational significance can be justifiably compared to the three-day concert that took place the same summer in Upstate New York, but was never allowed to achieve similar traction in the collective psyche. In this meticulously layered investigation, not only does Thompson celebrate the extraordinary artistry of the most influential musicians of their era but he interrogates the deeper meaning of how public memory is created and — in this case — casually erased.

Interviewing attendees who came to the Harlem Cultural Festival as young people, as well as the performers themselves, Thompson immediately plunges the audience into the action in “Summer of Soul,” which begins with Stevie Wonder delivering a drum solo that Thompson — a drummer himself — proceeds to use as a recurring motif. The film gains irresistible musical momentum as the giants just keep coming: The Chambers Brothers singing “Uptown.” The 5th Dimension singing their famous “Aquarius”/“Let the Sunshine In” medley (complete with cosmic choreography). Mavis Staples and Mahalia Jackson delivering a mesmerizing rendition of “Precious Lord, Take My Hand.” The Pips dancing in impeccable, early-1960s form behind Gladys Knight before ceding the stage to the far more laid back but no less electrifying vibes of Sly and the Family Stone.

It will surprise no one that Sly wants to take us higher. So does “Summer of Soul,” which captures the ecstatic moment of creation while exerting its own euphoric pull as a restoration of Black culture at a particularly vibrant turning point. (The year 1969, one observer notes, is when the Negro died and Black was born.)

The 5th Dimension performing at the Harlem Cultural Festival in 1969. (Searchlight Pictures)

Using impressively comprehensive video footage taken by television producer Hal Tulchin, Thompson creates a sensuous time capsule in which the colors and textures of the era come back to vibrant life, from the oranges, yellows and lime greens of the musicians’ costumes to the sartorial flourishes of the crowd itself. “Summer of Soul” even evokes the distinctive aromas of a gathering that one eyewitness calls “the ultimate Black barbecue.”

“Summer of Soul” would be valuable if only because it preserves such a sublime moment of Black expression, pleasure and autonomy. But Thompson cleverly interweaves present-day interviews into the archival images, creating an illuminating palimpsest of equally moving and eerily timely narratives. Whereas most filmmakers — especially musicians — would let the performances play uninterrupted, Thompson carefully overlays interviews with critics, observers and sometimes the artists themselves, to create thumbnail histories of everything from New York politics and the moon landing (which also happened that summer) to the intersection of Black and Latin culture in Harlem and the role of gospel music in coping with collective trauma (“We didn’t have therapists,” Al Sharpton notes. “But we did have Mahalia Jackson.”)

The result is something akin to cinematic hypertext, and thanks to Thompson’s steady hand, the brief but deep dives are richly rewarding. As electrifying as the stage performances are in “Summer of Soul,” the film’s most moving moments arrive when the people who were there watch Tulchin’s footage for the first time: The 5th Dimension’s Billy Davis Jr. and Marilyn McCoo are brought to tears recalling their reception from an audience that hadn’t always accepted them as “Black enough,” while Musa Jackson — who was 5 years old when he attended the Harlem Cultural Festival with his parents — breaks down when he realizes that the memories he nurtured for five decades have finally been validated. “I’m not crazy,” he says toward “Summer of Soul’s” conclusion. He’s laughing and crying at the same time, and so are we.

PG-13. At area theaters; also available on Hulu. Contains some disturbing images, smoking and brief drug use. 117 minutes.