George Wein, the impresario who almost single-handedly turned the jazz festival into a worldwide phenomenon, died on Monday at his apartment in Manhattan. He was 95.

His death was announced by a spokeswoman, Carolyn McClair.

Jazz festivals were not an entirely new idea when Mr. Wein (pronounced ween) was approached about presenting a weekend of jazz in the open air in Newport, R.I., in 1954. There had been sporadic attempts at such events, notably in both Paris and Nice in 1948. But there had been nothing as ambitious as the festival Mr. Wein staged that July on the grounds of the Newport Casino, an athletic complex near the historic mansions of Bellevue Avenue.

With a lineup including Billie Holiday, Dizzy Gillespie, Oscar Peterson, Ella Fitzgerald and other stars, the inaugural Newport Jazz Festival drew thousands of paying customers over two days and attracted the attention of the news media. It barely broke even; Mr. Wein later recalled that it made a profit of $142.50, and that it ended up in the black only because he waived his $5,000 producer’s fee.

But it was successful enough to merit a return engagement, and before long the Newport festival had established itself as a jazz institution — and as a template for how to present music in the open air on a grand scale.