Nick Timiraos:

Last week’s WSJ/NBC poll found that Americans, by more than two to one, are more worried about their ability to get ahead financially than they are about the widening income gap.

A new book by Robert Putnam, the Harvard University political scientist, delivers some detailed insights into what’s behind those worries. Mr. Putnam joins President Barack Obama and Arthur Brooks, president of the American Enterprise Institute, for a discussion on poverty at Georgetown University on Tuesday.

Mr. Putnam drew attention to the growing segregation of America along class lines at a conference hosted last month by the Federal Reserve on economic mobility in which he outlined key themes from the book, “Our Kids: The American Dream in Crisis.”

Even as Americans have become less segregated across racial and religious lines than they were a generation ago, they have grown more segregated along class lines. Americans are much less likely to go to school, live with, or marry people from different socioeconomic backgrounds, Mr. Putnam said.