This study draws upon 22,680 children from the 2002 National Survey of America's Families to investigate the demographic and family characteristics and well-being of stepchildren who have been adopted by a stepparent (n = 140) relative to children with 2 biological parents, children with 2 adoptive parents, and children with 1 biological parent and 1 nonadoptive stepparent. Five percent of all stepchildren and one quarter of all adopted children have been adopted by a stepparent. How the characteristics of adopted stepchildren compare to those of other children depends on the child's age—whereas younger adopted stepchildren are most similar to children with 2 biological parents, older adopted stepchildren are most similar to nonadopted stepchildren. Adopted stepchildren of all ages have significantly more behavior and emotional problems than children with 2 biological parents, but have similar levels of school engagement. There were no significant differences between children with 2 adoptive parents, nonadopted stepchildren, and adopted stepchildren on any measure of well-being regardless of the child's age. Implications for practice and policy include increasing awareness of adopted stepchildren and paying greater attention to the legal context under which stepchildren are adopted.