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Peter Yarrow, whose caring and righteous vocals for the trio Peter, Paul and Mary helped establish them as one of the most popular folk acts of the 1960s, died on Tuesday at his home on the Upper West Side of Manhattan. He was 86.

His death was confirmed by Ken Sunshine, his publicist. Mr. Sunshine said the cause was bladder cancer, which Mr. Yarrow had been battling for the past four years.

On many of the trio’s recordings they split the vocal parts equally, braiding Mr. Yarrow’s precise tenor around Noel Paul Stookey’s gentle baritone and Mary Travers’s warm contralto. But Mr. Yarrow also had some prominent lead vocals as well, fronting such well-known group recordings as “Puff the Magic Dragon,” “Day Is Done” and “The Great Mandala,” all of which he either wrote or co-wrote. “Puff” became a No. 2 Billboard hit, while “Day Is Done” grazed the Top 20.

Mr. Yarrow wrote many other songs recorded by the group, often in collaboration with Mr. Stookey, the last surviving member of the group (Ms. Travers died in 2009 at 72).

In their peak years, Peter, Paul and Mary reached the Billboard Top 40 12 times; six of those songs made it onto the Top 10, including one, their cover of John Denver’s “Leavin’ on a Jet Plane,” that reached No. 1. They racked up five Billboard Top 10 albums and twice topped the magazine’s album chart.