Journalist Lauren Sandler is an only child and the mother of one. After investigating what only children are really like and whether stopping at one child is an answer to reconciling motherhood and modernity, she learned a lot about herself - and a lot about our culture's assumptions. In this heartfelt work, Sandler legitimizes a discussion about the larger societal costs of having more than one.

Between the recession, the stresses of modern life, and the ecological dangers ahead, there are increasing pressures on parents to think seriously about singletons. Sandler considers the unique ways that singletons thrive and why so many of their families are happier. One and Only examines these ideas, including what the rise of the single-child family means for our economies, our environment, and our freedom, leaving the listener "informed and sympathetic", writes Nora Krug in the Washington Post.

Through this journey, "Sandler delves deeply, thoughtfully, and often humorously into history, culture, politics, religion, race, economics, and of course, scientific research", writes Lori Gottlieb, The New York Times Book Review. At the end, Sandler has quite possibly cracked the code of happiness, demonstrating that having just one may be the way to resolve our countless struggles with adulthood in the modern age.