Using the Los Angeles Family and Neighborhood Survey (L.A. FANS), this paper examines the association between the presence of co-resident extended kin and children's internalizing and externalizing behaviors. The paper demonstrates the differential role of extended kin by family structure, as well as across parental immigrant status – specifically, nativity and documentation status. Children in the sample were found to be disadvantaged in extended family households, especially with regard to internalizing behaviors. This disadvantageous association was found mostly among married-parent extended family households, whereas there was no association between the presence of extended kin and behavior problems in children from single-parent families. This pattern emerged more clearly among children of documented immigrants, compared to those with native-born parents and those whose parents were unauthorized immigrants. These findings suggest a need to modify previous theories on extended family living arrangements; they also provide policy implications for immigrant families. (Author abstract)