Holland Cotter reviews the exhibition “¡Presente! The Young Lords in New York,” held in three parts at the Bronx Museum of the Arts, El Museo del Barrio and Loisaida Inc., for The New York Times.

On July 26, 1969, a group of young Latinos stood in the band shell in Tompkins Square Park, in the East Village, and made an announcement. They were founding a New York branch of a revolution-minded political party called the Young Lords.

Inspired by the Black Panthers and an earlier street-gang-turned-activist Young Lords group in Chicago, their purpose was to gain social justice for New York’s working-class Latino population, then largely Puerto Rican and treated with contempt by the city government.

Most of the members onstage that day were recent college graduates well versed in leftist political theory. To gain the trust and cooperation of Latino communities — concentrated in the East Village, East…