Parent and teacher data for 14,990 children from the National Longitudinal Survey of Children and Youth were used in multilevel analyses to examine the relationship between ethnicity, children's aggression and emotional problems, and parenting. Using parent and teacher report, relationships between ethnicity and child behavior were present but modest. The association between parental harshness and child aggression differed between ethnic groups and across informants. Using teacher report of outcomes, parental harshness was positively related to child aggression in European Canadian families but negatively related in South Asian Canadian families. For all ethnic groups, parental harshness was positively related to children's aggression when parent report of outcomes was used, but relationships varied in strength across ethnic groups. The relationship of parental harshness with child emotional problems did not differ across groups, irrespective of informant. The results are discussed within the context of an ecological model of parenting.