Van Peebles’s Harlem Street

Look out, “Hair.” Peace and love (not war) may rule in Central Park at the Delacorte Theater, but they’re not the only free musical game in town. The pimps and whores and crooked cops of Melvin Van Peebles’s “Ain’t Supposed to Die a Natural Death” reign uptown in a lively Classical Theater of Harlem production at Marcus Garvey Park. (Presented by City Parks Theater, “Ain’t” moves to other locations in the coming weekends.)

Mr. Van Peebles’s show — he wrote the book, music and lyrics — tweaks the conventions of musical theater when it doesn’t dispense with them outright. A series of loosely strung together vignettes, it’s short on plot and traditional songs, but long on innovation. The characters — there’s also a drag queen, a lesbian, a disgruntled postal worker, a blind man, a fat guy — take turns in the spotlight delivering numbers that are half-sung or declaimed or even, yes, sort of rapped. They’re backed by a cool jazz-inflected accompaniment (lots of muted Miles Davis-type trumpet) with touches of gospel, soul and funk. The music still sounds great. It must have seemed radical when “Ain’t” opened on Broadway in 1971, the same year Mr. Van Peebles’s “Sweet Sweetback’s Baadasssss Song” was shaking things up in movie theaters.

The outdoor setting is a mixed blessing. On Tuesday people wandered in, stayed a bit and moved along; boys rode through on their bikes. It all seemed to meld with the street life onstage. The intensity of the production, though, at times dissipated in the warm night air.

Mr. Van Peebles is a flamboyant showman with a fondness for the down and dirty, and “Ain’t” is mostly a flamboyantly enjoyable show. The director, Alfred Preisser, has created a fast-moving, visually appealing production with a strong cast. He’s helped by Kimberly Glennon, who’s responsible for the just-right and sometimes pleasingly over-the-top costumes (oh, that bright pink Afro wig!); the ace music director, William (Spaceman) Patterson; and the versatile choreographer Tracy Jack.

What makes “Ain’t” distinctive, though, also compromises its dramatic power. While most of the numbers are sharp on their own, they don’t quite jell into a compelling whole. Emotion drives the best ones: the lesbian’s callout to her girlfriend in prison; a convict’s erotically charged evocation of his ex-lover that ends with a jolt in the electric chair. These characters snap into focus as individuals in a show mostly populated by types.

“Ain’t” sometimes feels like a hit parade of ’70s hot-button “ghetto” issues: poverty, alcoholism, drugs, violence, police harassment. The anger is real, but unmoored from a story line it sparks more recognition than resonance.