This study investigated the relationship between parental separation and aggressive and internalizing behavior in a large sample of Swiss children drawn from the ongoing Zurich Project on the Social Development of Children and Youths. Parents retrospectively reported life events and problem behavior for the first 7 years of the child’s life on a quarterly basis (N = 995; 28,096 time points) using an Event History Calendar. The time sequences of separation and child problem behavior were analyzed. Parental separation affected both aggressive and internalizing behavior even when maternal depression, financial difficulties, and parental conflict were included. Parental separation exerted a direct effect on child problem behavior as well as an indirect effect via maternal depression.