Whatever proximate variables are examined, their differential effects on rural and urban fertility are small. This indicates that no major disturbance has taken place in urban or rural reproductive norms. However, two possible reasons for the converging pattern of rural and urban fertility in Nigeria are identified. One is that urban mothers in the first half of the childbearing age range have higher fertility than their rural counterparts. The other is that breast-feeding and post-partum abstinence, which are the major determinants of marital fertility, exert a more depressing influence on rural than urban fertility.