Half of all pregnancies in the United States are either unplanned or unintended. Moreover, while fewer people are getting married, childbearing outside of wedlock is on the rise. These trends suggest that couples who have unplanned children are ambivalent or unenthusiastic about becoming parents, or, at the very least, are unprepared for parenthood. What kind of future does this mean for their kids . . . and for society as a whole?

In Generation Unbound, nationally known budget expert Isabel V. Sawhill presents likely causes for the recent changes in the traditional family structure, such as the increase in women's economic opportunities, declining economic prospects of men, access to birth control and abortion, and new social norms that allow young people more choices - but provide less guidance on what it means to be an adult.

Sawhill reveals an emerging class divide in patterns of marriage and childbearing: at the top of the ladder are "planners," who are marrying and having children only after establishing a career; at the bottom, and increasingly in the middle, are "drifters" who are having children early, outside of marriage, and without the stable support of the second parent.

Sawhill sees merit in the views of those on the political left, who argue for more social support for the drifters, including expanded child care, parental leave, family-friendly workplaces, and financial assistance, and for those on the right who argue for restoring traditional marriage so that children are raised in a stable family. But, she also points out that while collective responses are needed, they alone can't solve the problem. Any such efforts must be combined with the exercise of greater personal responsibility by potential parents themselves.