A B S T R A C TThe article explores a series of questions and hypotheses related to polygynous family structures and both household and individual-level food security outcomes, using the World Bank Living Standards Measurement Survey data from Nigeria, collected in 2011, 2013 model is used to examine the relationship between polygyny and household-level food security, and the degree to which it is mediated by household wealth, size, and livelihood. A Household Fixed Effect model is employed to explore whether a mother's status as monogamous versus polygynous relates systematically to her child's health, and also whether child outcomes of senior wives are better than outcomes of junior wives within polygynous households. At the household level, polygynous households are found to have better food security outcomes than monogamous households with differences in household composition and agricultural livelihood as potential explanatory mechanisms. At the individual level, however, children of polygynous mothers have worse nutrition outcomes than children of monogamous mothers in the long run. Within polygynous households, children of junior wives appear to have better nutritional outcomes in the long run, compared to children of more senior wives.