:Here's another source from a poetry perspective (The Poetry Foundation): "A group of poets aligned with the New York School of painting in the 1950s and ’60s. A diverse group of writers, the main figures of the New York School are Frank O’Hara, John Ashbery, James Schulyer, Kenneth Koch, and Barbara Guest. Influenced by relationships and collaborations with painters such as Jackson Pollock, Willem de Kooning, Jasper Johns, and Larry Rivers, the New York School poets are known for their urbane wit, interest in visual art, and casual address. A second generation of New York School poets grew up in the 1960s and included Ted Berrigan, Alice Notley, Ron Padgett, and Anne Waldman." 

 :I think there can be little question that the term New York School began with a particular movement in painting and branched out from their to include certain other arts. I didn't branch out nearly as much as this article suggested when I first came upon it, however.