William Cowsill, at 58; was lead singer of The Cowsills

PROVIDENCE -- William Cowsill, the lead singer of the popular 1960s band The Cowsills, which inspired the TV series ''The Partridge Family," died Friday. He was 58, and the cause of death was not immediately known.

News of Mr. Cowsill's death reached his family shortly after a memorial service in Newport honoring his younger brother, Barry, who died after Hurricane Katrina flooded New Orleans in August.

''We couldn't believe it ourselves," said his brother, Richard Cowsill. ''It was a shocker. It caught us all off guard."

William Coswill, who lived in Calgary, had been suffering from emphysema, osteoporosis, Cushing syndrome, and other ailments, according to another brother, Robert.

The Cowsills recorded a series of top hits between 1967 and 1970, including ''The Rain, The Park and Other Things," ''Love American Style," ''Indian Lake," and ''Hair." They also were spokespersons for the American Dairy Association, appearing in commercials and print ads for milk.

Four Cowsill brothers played in the band: Barry on bass, Bill on guitar, Bob on guitar and organ, and John on drums. Their mother, Barbara, and little sister, Susan, eventually joined the group. They lived in Middletown.

The band's career began in Newport, where by 1965 they had a regular gig at a club. They were spotted by a producer for NBC's ''Today" show who booked them for an appearance that led to a record deal.

The family had their own television special in 1968.

The band, however, had an acrimonious breakup in the 1970s. William, the oldest member, moved to Canada about 30 years ago and played in a band called ''Blue Shadows," Richard Cowsill said.

Mr. Cowsill leaves two sons, Travis and Del.