In Such a Pretty Fat, Jen Lancaster learned how to come to terms with her body. In My Fair Lazy, she expanded her mind. Now the New York Times bestselling author gives herself—and her generation—a kick in the X, by facing her greatest challenge to date: acting her age.

Jen is finally ready to put away childish things (except her Barbie Styling Head, of course) and embrace the investment-making, mortgage-carrying, life-insurance-having adult she’s become. From getting a mammogram to volunteering at a halfway house, she tackles the grown-up activities she’s resisted for years, and with each rite of passage she completes, she’ll uncover a valuable—and probably humiliating—life lesson that will ease her path to full-fledged, if reluctant, adulthood.