The buzz these days is that American politics may be entering a “postpartisan” era, as a new generation finds the old ideological quarrels among baby boomers to be increasingly irrelevant. In reality, matters are not so simple. Far from being postpartisan, today’s young adults are significantly more likely to identify as Democrats than were their predecessors. Along with colleagues at the Brookings and Hoover institutions, we recently completed a comprehensive study of the nation’s polarization. Our research concludes not only that the ideological differences between the political parties are growing but also that they have become embedded in American society itself.