One parent not connected to the study, William Draves of River Falls, Wisc., is skeptical about whether time limits or similar restrictions do much. He says they may even be counterproductive, so he sets no limits and uses no filtering software on his 18-year-old son, even letting him connect wirelessly from the roof when he wants.

"The Internet is going to be their life," he said. "This is how they are going to earn their living. This is how we communicate. This is the central feature of a middle-class lifestyle."

The Pew study is based on random telephone calls with 1,100 children 12 to 17 years old and their parents. They were conducted Oct. 26 to Nov. 28. The main findings have a margin of sampling error of plus or minus 3 percentage points.

The survey also finds that of the 13 percent of American teens who do not use the Internet, about half were once online but dropped out. They are most likely to blame lack of interest or access, followed by concern about safety. A small percentage say their parents no longer let them use the Internet.

Those who never had access are most likely to cite lack of interest or being busy, with lack of access ranking third.

Separately, Pew reported Thursday that the percentage of older Americans online continues to grow. A Jan. 13-Feb. 9 phone survey of 2,201 adults finds 26 percent of those age 65 and up with Internet access, an increase from 22 percent last March.

Older Americans embrace e-mail and research on the Web but shun "high trust" activities such as e-commerce, banking and online auctions. Pew expects the pattern to shift with the aging of Baby Boomers who are already familiar with those activities.