A total of 570 women in the second trimester of pregnancy were recruited from obstetric clinics for the Wisconsin Study of Families and Work. The 560 women who had live births were interviewed and given questionnaires at 1, 4, and 12 months postpartum (infancy period) and when the children were ages 2, 3 1/2, and 4 1/2 years (toddler/preschool period). During the spring of the children's kindergarten year, mothers and teachers were interviewed by telephone and were administered the MacArthur Health and Behavior Questionnaire, a newly developed multidimensional instrument for middle childhood assessment. The depression section of the National Institute of Mental Health Diagnostic Interview Schedule was used to diagnose any episodes of maternal major depression that occurred in the infancy or preschool period. Also, throughout the Wisconsin study, the Partner Role Quality Scale has been used to assess overall marital quality. The analysis was conducted on the 406 families with complete data on all variables of interest. For these families, the mothers reported major depression and marital conflict on multiple occasions in the child's infancy and toddler/preschool periods. The study found that children manifested co-occurring internalizing and externalizing symptoms, although internalizing was predominant for girls and externalizing for boys. Boys exposed to maternal depression in infancy, however, had a preponderance of internalizing behaviors, but if subsequently exposed to marital conflict, the mix toward externalizing behaviors increased to match levels of clinic-referred children. For girls, the preponderance of internalizing symptoms increased to match levels of clinic-referred children when initial exposure to marital conflict occurred in the toddler/preschool period. The authors advise that it is important to consider both maternal depression and marital conflict across developmental periods, to distinguish the symptom severity from direction (internalizing and externalizing), and to consider the child's gender. Prevention and intervention based on these findings are warranted. 4 tables, 2 figures, and 53 references