Increasingly children whose parents no longer live together are living in two households, alternating between family contexts. A growing literature documents strong, descriptive heterogeneities in children’s wellbeing across living arrangements. We combine longitudinal survey and administrative population data on 6000 Danish children born in 1995 to study how children’s emotional and behavioral problems change following parental union dissolution. Extending the existing, predominantly descriptive literature, we use several panel regression strategies that aim to control for unobservable confounding together with repeated measurement of the Strength and Difficulties Questionnaire to study children’s problems increase after parental union dissolution and examine heterogeneity across post-dissolution living arrangements. We find a substantial increase in emotional and behavioral problems following union dissolution, but only little evidence for substantial heterogeneity existing across post-dissolution family constellations and living arrangements. Our findings indicate that not only there is casual effect of parental union dissolution on children’s long-term wellbeing, but also that existing descriptive findings on differences across living arrangements likely are due to selection.