This study highlights the heterogeneity in two-parent families and examines how adolescents fare when they reside in simple two-parent, blended, and stepfamilies. Using the National Longitudinal Study of Adolescent Health (N= 1,769), we find that shared biological children in blended families have worse outcomes than children in simple two-parent families, even though they reside with both of their biological parents. These differences occur for academic performance, delinquency, school detachment, and depression. Current explanations in the family literature do not account for the poorer outcomes of shared children in blended families. We suggest that the presence of half-siblings creates a unique family situation that is not accurately represented in the current family literature.