Genetic factors can play a role in the multiple level of analyses approach to understanding the development of child psychology. The present study examined gene-environment correlations and Gene x Environment interactions for polymorphisms of three target genes, the serotonin transporter gene, the D4 dopamine reactor gene, and the monoamine oxidase A gene in relation to symptoms of anxiety, depression, and oppositional behavior. Saliva samples were collected from 175 non-Hispanic White, 4-year-old children. Psychosocial risk factors included socioeconomic status, life stress, caretaker depression, parental support, hostility, and scaffolding skills. In comparison with the short forms (s/s, s/l) of the serotonin transporter linked polymorphic repeat, the long form (l/l) was associated with greater increases in symptoms of child depression and anxiety in interactions with caretaker depression, family conflict, and socioeconomic status. In boys, low-activity monoamine oxidase A gene was associated with increases in child anxiety and depression in interaction with caretaker depression, hostility, family conflict, and family stress. The results highlight the important of gene-environment interplay in the development of symptoms of child psychopathology in young children.