Experiencing a parental divorce or separation and subsequently living in a reconstituted family, with a stepparent and stepsiblings or half-siblings, has become an increasingly common experience for children in Sweden during the last decades of the 20th century. Most children with separated parents will experience their parent finding a new partner and a relatively large share of Swedish children have either an older or younger half-sibling. In this doctoral thesis Jani Turunen explores children's experience of stepfamily formation and their emotional and educational outcomes in stepfamilies and other post-separation family forms. The thesis consists of three separate, yet related, studies that analyze different aspects of stepfamily dynamics in contemporary Sweden, a country often considered a forerunner in family demographic behaviors.