In August 2010 I wrote an article for The New York Times Magazine called “What Is It About 20-Somethings?” that took a new look at young people between the ages of 18 and 29 who seemed to be stuck in adolescence, either unable—or uninterested—in taking on the responsibilities of adulthood. Was this period a new rite of passage? Or sheer self-indulgence? The article hit a nerve and went viral, becoming the #1 most emailed NYTimes magazine article of the year and the most-shared article on Facebook. Inevitably, publishers soon asked me to expand the article into a book. “Only with my daughter,” I told them.