This year’s Whitney Biennial, considered the country’s most important showcase of contemporary art, has 75 participating artists — and one who has already withdrawn.

The biennial, no stranger to controversy, is an indicator of currents in the field as well as a career booster for the artists included. Past editions have sparked debates over identity and representation, but this year, before the list of participants was even released, a Chicago-based artist, Michael Rakowitz, pulled out of the exhibition in a protest against a museum vice chairman, Warren Kanders. Mr. Kanders is the chief executive of a company that manufactures equipment, including body armor and tear gas, for law enforcement agencies and militaries. The New York Times received a copy of Mr. Rakowitz’s letter to the curators, dated Dec. 18, withdrawing from the show.

The exhibition’s curators, Rujeko Hockley and Jane Panetta — both of whom work at the Whitney — said in an interview Sunday that they respected Mr. Rakowitz’s decision and regret that he won’t be involved in the biennial’s 79th iteration, for which they tried to bring together “as broad a range of artists as we could in all kind of senses of that word, whether that’s medium-wise, interest-wise, geographically, demographically, generationally,” in Ms. Hockley’s words.

Indeed, the list of participants, which The Times has previewed, is very diverse. Among the more high-profile names are Nicole Eisenman, Jeffrey Gibson, Barbara Hammer and Wangechi Mutu. People of color are a majority, and it’s one of the youngest groups in the biennial’s history, with three-quarters of the participants under the age of 40. Only five have ever exhibited in a Whitney Biennial before.