"I do not want more distractions," he says. "As it is, I am deluged with email. My friends and colleagues have ready access to me and I don't really want another service that I would feel obliged to check into on a frequent basis."
Kleinrock says his resistance is generational, but discomfort with technology isn't a factor.
After all, Kleinrock is arguably the world's first Internet user. The University of California, Los Angeles professor was part of the team that invented the Internet. His lab was where researchers gathered in 1969 to send test data between two bulky computers —the beginnings of the Arpanet network, which morphed into the Internet we know today.
"I'm having a 'been-there, done-that' feeling," Kleinrock says. "There's not a need on my part for reaching out and finding new social groups to interact with. I have trouble keeping up with those I'm involved with now."
Thomas Chin, 35, who works at an advertising and media planning company in New York, says he may be missing out on what friends-of-friends-of-friends are doing, but he doesn't need Facebook to connect with family and closer acquaintances.
"If we're going to go out to do stuff, we organize it (outside) of Facebook," he says.
Some people don't join the social network because they don't have a computer or Internet access, are concerned about privacy, or generally dislike Facebook. Those without a college education are less likely to be on Facebook, as are those with lower incomes. Women who choose to skip Facebook are more likely than men to cite privacy issues, while seniors are more likely than those 50-64 years old to cite computer issues, according the AP-CNBC poll.
About three-quarters of seniors are not on Facebook. By contrast, more than half of those under 35 use it every day.
The poll of 1,004 adults nationwide was conducted by GfK Roper Public Affairs and Corporate Communications May 3-7 and has a margin of sampling error of plus or minus 3.9 percentage points.