Using data from the National Educational Longitudinal Study (NELS), we found that teenagers who live in nonmarried families are less likely to graduate from high school or to attend college, more likely to smoke or drink, and more likely to initiate sexual activity. Not all nonmarried families are alike, however. In particular, teenagers living with their single mothers and with at least one grandparent in multigenerational households have developmental outcomes that are at least as good and often better than the outcomes of teenagers in married families. These findings obtain when a wide array of economic resources, parenting behavior, and home and school characteristics are controlled for.