Overall, 63 percent say they know someone who has, while 31 percent say they do not. Demographically, Americans with higher incomes and education levels are more likely to know someone who has cheated on their spouse than Americans with lower incomes and less education. In addition, those who live in the West and South are more likely to know someone who has cheated than those from the Northeast and Midwest.
Americans who are divorced or separated are also more likely to know someone who has cheated on their spouse than Americans overall.
In addition, the poll found that most married Americans are satisfied with their marriage, at least when they compare it to their parents' marriage. Specifically, 55 percent think their marriage is better than that of their parents, while another 41 percent thinks it is the same. Just 3 percent think their marriage is worse than their parents.
Overall, Americans favor divorce over staying together if a marriage isn't working out, though by a lesser margin than they did 15 years ago. Forty-six percent favor divorce in such circumstances while 38 percent oppose - in 1995 a majority of 51 percent favored divorce.
Catholics and evangelical Christians tend to oppose divorce even if the marriage isn't working out. Americans who are currently married are divided on the subject, while a majority of those who are separated or divorced favor divorce under such circumstances.
And when it comes to what's better for kids growing up, Americans stand behind divorce as a better option than parents staying together and fighting all the time. Seven in 10 say it is better for kids to grow up with divorced parents in this case, as do six in 10 married parents.
Nevertheless, a majority of Americans (53 percent) thinks getting a divorce is too easy and should be made more difficult to obtain than it is now, while one in four Americans thinks getting a divorce should be made easier. These numbers are similar to those found in polls conducted by the University of Chicago over the past 20 years.
The poll was taken as part of CBS News' "Where America Stands" series, an in-depth look at where the country stands today on key topics and an outlook for the future decade.
See More Stories and Videos from the Series: Where America Stands
Read the Complete Poll
More Results from the Poll:
• Most working parents feel torn at least some of the time between the demands of their jobs and wanting to spend more time with their families, and a third say they feel torn frequently. Just one in five parents who work say they feel torn between work and family life only rarely.
• When it comes to eating dinner together as a family, most parents say they do. Three in four parents say that in a typical week, their family eats dinner together most of the time, though more moms than dads say so.
• When those families do eat dinner together, they are usually able to keep modern communication devices from disrupting the meal. Most parents say their family members never text, e-mail or talk on the cell phone during dinner. They are less successful about keeping television out of the dinner hour, however. More than half of parents say the television is turned on during dinner at least some of the time, including one in three parents who say it's always on during dinner.
Family therapist Dr. Jenn Berman offered some perspective on the poll's findings, on "The Early Show":
This poll was conducted among a random sample of 1048 adults nationwide, interviewed by telephone December 17-22, 2009. Phone numbers were dialed from random digit dial samples of both standard land-line and cell phones. The error due to sampling for results based on the entire sample could be plus or minus three percentage points. The error for subgroups is higher.
This poll release conforms to the Standards of Disclosure of the National Council on Public Polls.