The author attempts to identify the determinants of infant mortality in developing countries and, in particular, to overcome some of the deficiencies of a previous study by G. B. Rodgers. The roles of income and inequality as determinants of infant mortality are first examined. Next, consideration is given to the effects of education and medical care. A selection of regression results is then presented. The results provide some evidence as to why infant mortality rates, which fell rapidly in the two decades following World War II, stabilized in the late 1960s and 1970s. They also suggest that developing countries that place low priority on improving women's education and on attaining a more egalitarian distribution of incomes are unlikely to achieve a rapid reduction in their infant mortality rates.