This study investigated the association between average income or deprivation and infant mortality rate across neighborhoods of 4 world cities. Using a maximum likelihood negative binomial regression model that controls for births, we analyzed data for 1988–1992 and 1993–1997. In Manhattan, for both periods, we found an association (.05% significance level) between income and infant mortality. In Tokyo, for both periods, and in Paris and London for period 1, we found none (5% significance level). For period 2, the association just missed statistical significance for Paris, whereas for London it was significant (5% level). The authors concluded, in stark contrast to Tokyo, Paris, and London, the association of income and infant mortality rate was strongly evident in Manhattan.