About half of young Americans expect to be financially better off than their parents, according to a new poll, a sign that the dream of upward mobility is alive but somewhat tempered.

The poll, by The Associated Press-NORC Center for Public Affairs Research and MTV, found that half of 15- to 26-year-olds think they eventually will be better off than their parents in terms of household finances. About 29 percent expect to do as well as their parents, and 20 percent expect to be worse off.

Parents were slightly more optimistic: 60 percent think their children will do better than they did, a view...