Changing family relationships as a result of divorce are considered a potential threat to children's well-being. This study investigates the well-being of children under the age of eight years in Finnish stepfamilies from the viewpoint of the mother. The goal of this study is to explore how the structural characteristics of the stepfamily and the functioning of its various relationships are linked to a child's well-being. The survey data used in this research are drawn from a sample of 667 stepfamilies. The results indicate that a child's well-being was best supported by the well-functioning relationships within the stepfamily: there was a distinct connection between a child's problems and negative quality of relationships. (Contains 5 tables and 1 note.)