This paper examines changes in children's living arrangements and well-being using the 1997, 1999, and 2002 rounds of the National Survey of America's Families (NSAF). Between 1997 and 2002, the share of young children and lower-income children living with a single mother declined while the share living with married biological/adoptive parents as well as with unmarried cohabiting parents increased. In 2002, children living with either married biological/adoptive parents or married stepparents experienced less material hardship than children living with single mothers, cohabiting parents, or cohabiting stepparents. School aged children and teens living with their own two parents (whether married or not) are less likely to exhibit behavioral problems than children living with single mothers, married stepparents, or unmarried stepparents. Between 1997 and 2002, children in single-mother families enjoyed larger improvements in material well-being than children in other arrangements.